ci: add workspace/lockfile job (#805)

See rust-random/rand#1739

Author: newpavlov

.github/workflows/workspace.yml

@@ -122,3 +122,11 @@ jobs:
     steps:
       - uses: actions/checkout@v6
       - uses: crate-ci/typos@v1
+
+  lockfile:
+    name: Check Cargo.lock
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: dtolnay/rust-toolchain@stable
+      - run: cargo check --workspace --locked