Update GitHub Actions action versions (#217)

Author: Klaus Rettinghaus

.github/workflows/build.yml

@@ -35,7 +35,7 @@ jobs:
             TOXENV: typing
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v4

.github/workflows/publish.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Set up Python 3.9
       uses: actions/setup-python@v4

.github/workflows/tests.yml

@@ -17,7 +17,7 @@ jobs:
         python-version: ["3.8", "3.9", "3.10", "3.11", "pypy3.8"]
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v4