ci: remove stale cache action version comment

Author: wochinge

.github/workflows/ci.yml

@@ -46,7 +46,7 @@ jobs:
           version: "0.11.2"
           python-version: "3.13"
           enable-cache: true # zizmor: ignore[cache-poisoning] CI-only, no artifacts published
-      - uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.4 # zizmor: ignore[cache-poisoning]
+      - uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # zizmor: ignore[cache-poisoning]
         name: Cache mypy cache
         with:
           path: ./.mypy_cache