chore(ci): build with --locked flag

Author: orhun

.github/workflows/rust.yml

@@ -17,6 +17,6 @@ jobs:
     - uses: actions/checkout@v2
     - uses: Swatinem/rust-cache@v2
     - name: Build
-      run: cargo build --verbose
+      run: cargo build --locked --verbose
     - name: Run tests
       run: cargo test --verbose