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

.github/workflows/coverage.yml

@@ -2,6 +2,8 @@ name: coverage
 
 on: [push, pull_request]
 
+permissions: {}
+
 jobs:
   coverage:
     if: github.repository == 'Swatinem/rust-cache'
@@ -17,11 +19,15 @@ 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 --component llvm-tools-preview --no-self-update
 
-      - uses: taiki-e/install-action@cargo-llvm-cov
+      - uses: taiki-e/install-action@cd39cb0572834c149bf3533a143f05e09def0f3c # v2.62.2
+        with:
+          tool: cargo-llvm-cov
 
       - uses: ./
         with: