ci: address lint findings, add zizmor workflow (#262)

.github/workflows/target-dir.yml

@@ -2,6 +2,8 @@ name: target-dir
 
 on: [push, pull_request]
 
+permissions: {}
+
 jobs:
   target-dir:
     if: github.repository == 'Swatinem/rust-cache'
@@ -17,7 +19,9 @@ jobs:
       CARGO_TERM_COLOR: always
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        with:
+          persist-credentials: false
 
       - run: rustup toolchain install stable --profile minimal --no-self-update