workflows: Add zizmor ignore comment

Should be fine to use check-latest-spec-version from master.

Signed-off-by: Jussi Kukkonen <jkukkonen@google.com>

Author: jku

.github/workflows/specification-version-check.yml

@@ -33,6 +33,6 @@ jobs:
       contents: read
       issues: write
     needs: get-supported-tuf-version
-    uses: theupdateframework/specification/.github/workflows/check-latest-spec-version.yml@master
+    uses: theupdateframework/specification/.github/workflows/check-latest-spec-version.yml@master # zizmor: ignore[unpinned-uses]
     with:
       tuf-version: ${{needs.get-supported-tuf-version.outputs.version}}