check pyi generations are up to date (#1786)

.github/workflows/check_generated_pyi.yml

@@ -0,0 +1,32 @@
+name: check-generated-pyi
+
+on:
+  push:
+    branches: [ "main" ]
+    # We don't just trigger on pyi_generator.py and the components dir, because
+    # there are other things that can change the generator output
+    # e.g. black version, reflex.Component, reflex.Var.
+    paths-ignore:
+      - '**/*.md'
+  pull_request:
+    branches: [ "main" ]
+    paths-ignore:
+      - '**/*.md'
+
+jobs:
+  check-generated-pyi-components:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./.github/actions/setup_build_env
+        with:
+          python-version: "3.11.5"
+          run-poetry-install: true
+          create-venv-at-path: .venv
+      - run: |
+          poetry run python scripts/pyi_generator.py
+          if git diff; then
+            echo "No diffs - AOK!"
+          else
+            echo "ERROR: pyi_generator.py output is out of date. Please run scripts/pyi_generator.py and commit the changes."
+          fi