github: Separate compatibility tests in own workflow

.github/workflows/rust.yml

@@ -21,9 +21,13 @@ jobs:
     - uses: actions/checkout@v3
     - name: Build
       run: cargo build --verbose
-    - name: Run Rust tests
+    - name: Test
       run: cargo test --verbose
-    - name: Run compatibility tests
+
+  test-compat:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Test
       run: make test
 
   build-wasm: