CI: Update mypy workflow (#13574)

* Fix pyproject.toml

* Add TODO

* Update mypy workflow

.github/workflows/code-checks.yml

@@ -13,10 +13,10 @@ concurrency:
 jobs:
   mypy:
     runs-on: ubuntu-20.04
-    # todo: checking also lightning_app
     steps:
-    - uses: actions/checkout@master
-    - uses: actions/setup-python@v2
+    - uses: actions/checkout@v3
+
+    - uses: actions/setup-python@v3
       with:
         python-version: 3.9
 
@@ -37,6 +37,5 @@ jobs:
         pip install -r requirements/pytorch/devel.txt --find-links https://download.pytorch.org/whl/cpu/torch_stable.html
         pip list
 
-    - name: Type check PyTorch
-      working-directory: src
-      run: mypy pytorch_lightning --install-types --non-interactive --config-file ../pyproject.toml
+    - name: Check typing
+      run: mypy

pyproject.toml

@@ -22,7 +22,13 @@ line-length = 120
 
 
 [tool.mypy]
-files = ["pytorch_lightning"]
+files = [
+    "src/pytorch_lightning",
+    # TODO: Check typing in app source
+    # "src/lightning_app",
+]
+install_types = "True"
+non_interactive = "True"
 disallow_untyped_defs = "True"
 ignore_missing_imports = "True"
 show_error_codes = "True"