Avoid executing contracts-docs-publish parallelly

When `contracts-docs-publish` job is executed at a similar time for both Random
Beacon and ECDSA, it may happen that both jobs pull the
`auto-update-solidity-api-docs` branch at the same state and one of the jobs
will push a commit with updated docs, while the other won't be able to do that,
as the state of the branch will be different than when the pull happened.
The error we see in that case is following:
```
error: failed to push some refs to 'https://github.com/threshold-network/threshold.git'
hint: Updates were rejected because the remote contains work that you do
hint: not have locally. This is usually caused by another repository pushing
hint: to the same ref. You may want to first integrate the remote changes
hint: (e.g., 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.
```
To avoid such situations we add a `contracts-docs-prepublish-wait` job to each
workflow with a step that checks if any 'Publish contracts documentation'
worklow is currently running. If it detects such job, it will wait specified
time and check again. Only when no running job is detected, the steps will
succeed and the workflow will proceed to execution of the `Publish contracts
documentation` job.
As it's likely that both `contracts-docs-prepublish-wait` jobs will be run at a
similar time. we add a 10s wait in one of them, to avoid executing both at a
moment when no `Publish contracts documentation` is run yet in any workflow.

There is still a small change that both `Publish contracts documentation` jobs
will run at similar time and cause a failure of one of them, but in that
unlikely scenario, we can always rerun the failing job and it should pass on
that second run.

.github/workflows/contracts-ecdsa-docs.yml

@@ -49,6 +49,29 @@ jobs:
       commentPR: true
       exportAsGHArtifacts: true
 
+  # This job is needed to avoid a clash of `contracts-docs-publish` jobs for
+  # `random-beacon` and `ecdsa` projects (if both are run and pull the code at
+  # the same time and try to push to the same branch, one of them will fail). 
+  contracts-docs-prepublish-wait:
+    name: Wait for contracts docs to be published
+    needs: contracts-docs-publish-preview
+     # TODO: remove last OR
+    if: (github.event_name == 'release' && startsWith(github.ref, 'refs/tags/solidity/')) || github.ref == 'refs/pull/3534/merge'
+    runs-on: ubuntu-latest
+    steps:
+      # We want to minimize the risk the next step executes at the same time as
+      # the similar step in Random Beacon.
+      - name: Wait 10 seconds
+        run: sleep 10
+      - name: Wait for `random-beacon` docs to be published
+        uses: lewagon/[email protected]
+        with:
+          ref: ${{ github.ref }}
+          check-name: 'Publish contracts documentation'
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          # 120s is a value for testing purposes. TODO: change to 10s
+          wait-interval: 120
+
   # This job will be triggered for releases which name starts with
   # `refs/tags/solidity/`. It will generate contracts documentation in
   # Markdown and sync it with a specific path of
@@ -57,9 +80,7 @@ jobs:
   # commit pushing the changes will be verified using GPG key.
   contracts-docs-publish:
     name: Publish contracts documentation
-    needs: docs-detect-changes
-    # TODO: remove last OR
-    if: (github.event_name == 'release' && startsWith(github.ref, 'refs/tags/solidity/')) || github.ref == 'refs/pull/3534/merge'
+    needs: [docs-detect-changes, contracts-docs-prepublish-wait]
     uses: keep-network/ci/.github/workflows/reusable-solidity-docs.yml@main
     with:
       projectDir: /solidity/ecdsa

.github/workflows/contracts-random-beacon-docs.yml

@@ -49,6 +49,25 @@ jobs:
       commentPR: true
       exportAsGHArtifacts: true
 
+  # This job is needed to avoid a clash of `contracts-docs-publish` jobs for
+  # `random-beacon` and `ecdsa` projects (if both are run and pull the code at
+  # the same time and try to push to the same branch, one of them will fail). 
+  contracts-docs-prepublish-wait:
+    name: Wait for contracts docs to be published
+    needs: contracts-docs-publish-preview
+     # TODO: remove last OR
+    if: (github.event_name == 'release' && startsWith(github.ref, 'refs/tags/solidity/')) || github.ref == 'refs/pull/3534/merge'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Wait for `random-beacon` docs to be published
+        uses: lewagon/[email protected]
+        with:
+          ref: ${{ github.ref }}
+          check-name: 'Publish contracts documentation'
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          # 120s is a value for testing purposes. TODO: change to 10s
+          wait-interval: 120
+
   # This job will be triggered for releases which name starts with
   # `refs/tags/solidity/`. It will generate contracts documentation in
   # Markdown and sync it with a specific path of
@@ -57,7 +76,7 @@ jobs:
   # commit pushing the changes will be verified using GPG key.
   contracts-docs-publish:
     name: Publish contracts documentation
-    needs: docs-detect-changes
+    needs: [docs-detect-changes, contracts-docs-prepublish-wait]
     # TODO: remove last OR
     if: (github.event_name == 'release' && startsWith(github.ref, 'refs/tags/solidity/')) || github.ref == 'refs/pull/3534/merge'
     uses: keep-network/ci/.github/workflows/reusable-solidity-docs.yml@main