ci: update actions/checkout in GHA workflows to v4

Author: striezel

.github/workflows/clang.yml

@@ -11,7 +11,7 @@ jobs:
         version: [12, 13, 14]
     steps:
       # Checks-out the repository under $GITHUB_WORKSPACE.
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: 'recursive'
       - name: Install Debian packages

.github/workflows/gcc.yml

@@ -11,7 +11,7 @@ jobs:
         version: [9, 10, 11]
     steps:
       # Checks-out the repository under $GITHUB_WORKSPACE.
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: 'recursive'
       - name: Install Debian packages

.github/workflows/msys2.yml

@@ -10,7 +10,7 @@ jobs:
         shell: msys2 {0}
     steps:
       # Checks-out the repository under $GITHUB_WORKSPACE.
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: 'recursive'
       - uses: msys2/setup-msys2@v2