CI: bump actions/checkout to v4

.github/workflows/darker.yml

@@ -11,7 +11,8 @@ jobs:
   darker-lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - name: Checkout repo
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
       - uses: actions/setup-python@v4

.github/workflows/lynx.yml

@@ -22,7 +22,9 @@ jobs:
         python-version: [ "3.10" ]
 
     steps:
-      - uses: actions/checkout@v3
+      - name: Checkout repo
+        uses: actions/checkout@v4
+
       - name: Install latest Rust stable
         uses: actions-rs/toolchain@v1
         with:

.github/workflows/pr_release_note_entry.yml

@@ -14,5 +14,8 @@ jobs:
     name: 'Checking release note entry for PR ${{ github.event.number }}'
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
-      - run: ls -l ${{ github.workspace }}/newsfragments/ | grep -E '${{ github.event.number }}\.(feature|bugfix|doc|removal|misc|dev)\.rst'
+      - name: Checkout repo
+        uses: actions/checkout@v4
+
+      - name: Check for presence of newsfragment file
+        run: ls -l ${{ github.workspace }}/newsfragments/ | grep -E '${{ github.event.number }}\.(feature|bugfix|doc|removal|misc|dev)\.rst'

.github/workflows/python_tests.yml

@@ -20,7 +20,9 @@ jobs:
         python-version: [ "3.8", "3.11" ]
 
     steps:
-      - uses: actions/checkout@v3
+      - name: Checkout repo
+        uses: actions/checkout@v4
+
       - name: Install latest Rust stable
         uses: actions-rs/toolchain@v1
         with:

.github/workflows/ruff.yaml

@@ -12,7 +12,8 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
+      - name: Checkout repo
+        uses: actions/checkout@v4
 
       - name: Set up Python
         uses: actions/setup-python@v4