Re-enable semver-checks. (#1490)

### What

Re-enable semver-checks.

### Why

They should be unstuck now.

### Known limitations

N/A

.github/workflows/rust.yml

@@ -17,11 +17,7 @@ jobs:
     # temporarily disabling publish-dry-run, it appears to be broken with recent
     # changes to dependency specifications?
     # needs: [fmt, cackle, cargo-deny, check-git-rev-deps, build-and-test, publish-dry-run]
-    # needs: [fmt, cackle, cargo-deny, check-git-rev-deps, semver-checks, build-and-test]
-    # semver-checks is currently broken due to incompatible `arbitrary` crate 
-    # update (https://github.com/rust-fuzz/arbitrary/issues/203).
-    # TODO: re-enable this as soon as the check has been fixed.
-    needs: [fmt, cackle, cargo-deny, check-git-rev-deps, build-and-test]
+    needs: [fmt, cackle, cargo-deny, check-git-rev-deps, semver-checks, build-and-test]
     runs-on: ubuntu-latest
     steps:
     - if: contains(needs.*.result, 'failure') || contains(needs.*.result, 'cancelled')