feat: code formatting workflow

.github/workflows/code-formatting.yml

@@ -0,0 +1,74 @@
+name: Isort and Black Formatting
+# Incrementally reformat only changed files with black, all files with isort
+#
+# Replaces pre-commit.ci, since it reformats all the files.
+# See issue https://github.com/pre-commit-ci/issues/issues/90
+#
+# The action requires a custom token to trigger workflow after pushing reformatted files back to the branch.
+# `secrets.GITHUB_TOKEN` can be used instead, but this will result
+# in not running necessary checks after reformatting, which is undesirable.
+# For details see https://github.com/orgs/community/discussions/25702
+
+on:
+  pull_request_target:
+    paths:
+      - "**.py"
+    types: [opened, synchronize, reopened, labeled, unlabeled]
+
+defaults:
+  run:
+    shell: bash -x -e -u -o pipefail {0}
+
+jobs:
+  reformat_with_isort_and_black:
+    runs-on: ubuntu-latest
+    permissions:
+      # write permissions required to commit changes
+      contents: write
+    steps:
+      - name: Checkout branch
+        uses: actions/checkout@v4
+        with:
+          # setup repository and ref for PRs, see
+          # https://github.com/EndBug/add-and-commit?tab=readme-ov-file#working-with-prs
+          repository: ${{ github.event.pull_request.head.repo.full_name }}
+          ref: ${{ github.event.pull_request.head.ref }}
+          # custom token is required to trigger actions after reformatting + pushing
+          token: ${{ secrets.NEMO_REFORMAT_TOKEN }}
+          fetch-depth: 0
+
+      - name: Get changed files
+        id: changed-files
+        uses: step-security/changed-files@v45.0.1
+        with:
+          files: |
+            **.py
+
+      - name: Setup Python env
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.10"
+
+      - name: black
+        uses: psf/black@stable
+        if: ${{ steps.changed-files.outputs.any_changed == 'true' }}
+        with:
+          options: "--verbose"
+          # apply only to changed files (pass explicitly the files)
+          src: "${{ steps.changed-files.outputs.all_changed_files }}"
+          version: "~= 24.3"
+
+      - name: isort
+        uses: isort/isort-action@v1
+        if: ${{ steps.changed-files.outputs.any_changed == 'true' }}
+        with:
+          isort-version: "5.13.2"
+          # reformat all files with isort – safe since the whole repo is already reformatted
+          configuration: ""
+
+      - uses: EndBug/add-and-commit@v9
+        # Commit changes. Nothing is committed if no changes.
+        with:
+          message: Apply isort and black reformatting
+          commit: --signoff
+