Enable ruff check E303 (emscripten-core#23155)

This rule was lost in the recent switch from flake8.

This change brings back that rule which is currently in preview in ruff.

See emscripten-core#23139 (comment)

Author: cclauss

.circleci/config.yml

@@ -425,6 +425,8 @@ jobs:
       - checkout
       - pip-install
       - run: ruff check
+      # TODO (cclauss): When ruff supports rule E303 without --preview, remove following line
+      - run: ruff check --preview --select=E303
   mypy:
     executor: bionic
     steps:

pyproject.toml

@@ -49,11 +49,8 @@ lint.ignore = [
   "PLW1510",
   "PLW2901",
 ]
-
 lint.per-file-ignores."emrun.py" = [ "PLE0704" ]
-
 lint.mccabe.max-complexity = 48 # Recommended: 10
-
 lint.pylint.allow-magic-value-types = [
   "bytes",
   "float",