Add missing v prefix to action pin version comments

Resolves zizmor ref-version-mismatch warnings on hash-pinned actions whose
version comments omitted the leading v (the pinned commits already match the
corresponding vX.Y.Z tags). Comment-only change.

Part of STF-557.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: oschwald

.github/workflows/test.yml

@@ -23,7 +23,7 @@ jobs:
           submodules: true
           persist-credentials: false
       - name: Install the latest version of uv
-        uses: astral-sh/setup-uv@08807647e7069bb48b6ef5acd8ec9567f424441b # 8.1.0
+        uses: astral-sh/setup-uv@08807647e7069bb48b6ef5acd8ec9567f424441b # v8.1.0
       - name: Install tox
         run: uv tool install --python-preference only-managed --python 3.13 tox --with tox-uv --with tox-gh
       - name: Install Python