Give the staging client a version number that is different from QA

This should avoid a conflict when uploading files to Sentry due to having two
versions that are the same. It also makes it easy to verify that the client
being served by staging.hypothes.is is the correct one.

.github/workflows/release.yml

@@ -90,7 +90,7 @@ jobs:
       run: |
         git fetch --tags --quiet
         LAST_COMMIT_HASH=$(git show HEAD --no-patch --format="%h")
-        STAGING_VERSION=$(git tag --list | sort --version-sort --reverse | head -n1 | tail -c +2)-$LAST_COMMIT_HASH
+        STAGING_VERSION=$(git tag --list | sort --version-sort --reverse | head -n1 | tail -c +2)-stg-$LAST_COMMIT_HASH
         echo "STAGING_VERSION=$STAGING_VERSION" >> $GITHUB_ENV
     - name: Build app
       run: |