Use semver and PR branch name for Docker versions (#1486)

The existing config would use "1.8-something" for things built off main, which is more appropriately 1.9-dev. If it's not on main, this also adds the branch name, so it's instant to see in a deployed instance which feature branch it is running.

.github/workflows/docker.yml

@@ -77,7 +77,9 @@ jobs:
         run: |
           pip -q install setuptools_scm
           # '+' is not supported in Docker Image tags
-          echo "internetnl_version=$(python -m setuptools_scm)" | tr '+' '-'| tee -a "$GITHUB_OUTPUT"
+          scm_version=$(echo 'from setuptools_scm import get_version; print(get_version(version_scheme="release-branch-semver"))' | python)
+          branch_version_suffix=${GITHUB_HEAD_REF:+-$GITHUB_HEAD_REF}
+          echo "internetnl_version=$scm_version$branch_version_suffix" | tr '+' '-'| tee -a "$GITHUB_OUTPUT"
 
       # login to pull images from Github registry
       - name: Login to GitHub Container Registry