Check that the release tag has the expected format

Author: mbg

.github/workflows/update-proxy-release.yml

@@ -21,6 +21,14 @@ jobs:
     env:
       RELEASE_TAG: ${{ inputs.tag || 'codeql-bundle-v2.22.0' }}
     steps:
+      - name: Check release tag format
+        shell: bash
+        run: |
+          if ! [[ $RELEASE_TAG =~ "^codeql-bundle-v[0-9]+\.[0-9]+\.[0-9]+$" ]]; then
+            echo "Invalid release tag: expected a CodeQL bundle tag in the 'codeql-bundle-vM.N.P' format."
+            exit 1
+          fi
+
       - name: Install Node
         uses: actions/setup-node@v4