Fix automation for updating builder lifecycle version

Sets `GH_TOKEN` when calling `gh release view`, otherwise it returns
an empty payload (but still exits zero, sigh).

Also adjusts the PR creation step name to make it clearer that PRs
are also updated too.

GUS-W-14329446.

.github/workflows/update-lifecycle.yml

@@ -32,14 +32,16 @@ jobs:
       - name: Determine latest lifecycle version
         id: latest-version
         run: echo "version=$(gh release view --repo buildpacks/lifecycle --json tagName --jq '.tagName | sub("v"; "")')" >> "${GITHUB_OUTPUT}"
+        env:
+          GH_TOKEN: ${{ steps.generate-token.outputs.app_token }}
 
       - name: Update builder manifests with latest lifecycle version
         # This only updates manifests that were on the same version as builder-22, to ensure
         # that any legacy builder images pinned to older lifecycle versions are not updated too.
         run: sed --in-place --expression 's/^version = "${{ steps.existing-version.outputs.version }}"$/version = "${{ steps.latest-version.outputs.version }}"/' */builder.toml
 
-      # This step will skip creating a PR if there are no changes to commit.
-      - name: Create pull request
+      # Note: This step will skip creating a PR if there are no changes to commit.
+      - name: Create or update pull request
         id: pr
         uses: peter-evans/[email protected]
         with: