refactor(workflows): code formatting and linting

Overhaul workflow (jobs) for code formatting and linting,
i.e. Black, Flake8, isort: rename file, allow manual triggering
of workflow, set ENV variable for Python version, make equivalent
steps in individual jobs more consistent, give every step a name.
Use black profile for isort in setup.cfg to avoid redundancy.
Add SPDX identifiers.

.github/workflows/formatting_linting.yml

@@ -0,0 +1,69 @@
+# SPDX-FileCopyrightText: 2024 K Kollmann
+# SPDX-License-Identifier: MIT
+
+name: Code formatting and linting
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+      - main
+  workflow_dispatch:
+
+env:
+  PYTHON_VERSION: "3.9"
+
+jobs:
+  black:
+    name: Black code formatter
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v4.1.6
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+      - name: Run Black
+        uses: psf/black@24.4.2
+        with:
+          options: "--version --check --diff --color" # default: "--check --diff"
+
+  flake8:
+    name: Flake8 linter
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v4.1.6
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+      - name: Set up Python environment – ${{ env.PYTHON_VERSION }}
+        uses: actions/setup-python@v5.1.0
+        with:
+          python-version: ${{ env.PYTHON_VERSION }}
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade wheel pip
+          pip install .[lint]
+      - name: Show Flake8 version
+        run: flake8 --version
+      - name: Run Flake8
+        run: flake8 -v --show-source moviepy setup.py scripts docs/conf.py examples tests
+
+  isort:
+    name: isort import sorter
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v4.1.6
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+      - name: Set up Python environment – ${{ env.PYTHON_VERSION }}
+        uses: actions/setup-python@v5.1.0
+        with:
+          python-version: ${{ env.PYTHON_VERSION }}
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade wheel pip
+          pip install .[lint]
+      - name: Run isort
+        run: isort --check-only --diff moviepy setup.py scripts docs/conf.py examples tests

setup.cfg

@@ -40,13 +40,10 @@ docstring-convention = numpy
 #max-complexity = 10
 
 [isort]
+profile = black
 lines_after_imports = 2
-multi_line_output = 3
-line_length = 88
-use_parentheses = True
 combine_as_imports = True
-include_trailing_comma = True
-py_version = 36
+py_version = 39
 known_tests_third_party = pytest
 sections = STDLIB,THIRDPARTY,TESTS_THIRD_PARTY,FIRSTPARTY,LOCALFOLDER