Fix regex escaping in release.yaml for version check

Author: simonharrer

.github/workflows/release.yaml

@@ -33,7 +33,7 @@ jobs:
         id: versioncheck
         with:
           pyproject-path: "./pyproject.toml"
-          test-regex: '[0-9]+(\.[0-9]+)*([a-z]+[0-9]+)?(\.post[0-9]+)?(\.dev[0-9]+)?'
+          test-regex: '[0-9]+(\\.[0-9]+)*([a-z]+[0-9]+)?(\\.post[0-9]+)?(\\.dev[0-9]+)?'
       - name: check output
         run: |
           echo "Output: ${{ steps.versioncheck.outputs.local_version_is_higher }}"  # 'true' or 'false