ci: use --locked when installing cargo-msrv and cargo-audit (#746)

Author: kevinjqliu

.github/workflows/audit.yml

@@ -38,6 +38,6 @@ jobs:
     steps:
       - uses: actions/checkout@v6
       - name: Install cargo-audit
-        run: cargo install cargo-audit
+        run: cargo install cargo-audit --locked
       - name: Run audit check
         run: cargo audit

.github/workflows/rust.yml

@@ -51,7 +51,7 @@ jobs:
     steps:
       - uses: actions/checkout@v6
       - name: Install cargo-msrv
-        run: cargo install cargo-msrv
+        run: cargo install cargo-msrv --locked
       - name: Check
         run: |
           # run `cargo msrv verify` to see problems