Bump actions/checkout from 2 to 4 (#531)

Author: dependabot[bot]

.github/workflows/docs.yml

@@ -15,7 +15,7 @@ jobs:
         run: |
           python --version
       - name: Clone Git repository (without depth limitation)
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
       - name: Install dependencies

.github/workflows/python-versions.yml

@@ -24,7 +24,7 @@ jobs:
         run: |
           python --version
       - name: Clone Git repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           path: git-repo
       - name: Install Python package

.github/workflows/sounddevice-data.yml

@@ -22,7 +22,7 @@ jobs:
         run: |
           python --version
       - name: Clone Git repository (with submodules)
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           path: git-repo
           submodules: true