Add codegen CI job

Author: Sh3Rm4n

.github/workflows/ci.yml

@@ -83,3 +83,16 @@ jobs:
         with:
           command: fmt
           args: --all -- --check
+
+  codegen:
+    name: Check Codegen
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          override: true
+          profile: minimal
+          components: rustfmt
+      - run: cd codegen && cargo check