chore: configure Dependabot and update actions to latest version (#10)

Author: randh1r

.github/dependabot.yml

@@ -0,0 +1,10 @@
+# https://help.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
+
+version: 2
+
+updates:
+  # Maintain dependencies for GitHub Actions
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
     name: PHPCS
     steps:
     - name: Checkout
-      uses: actions/checkout@v2
+      uses: actions/checkout@v5
 
     - name: Setup
       uses: ./.github/actions/setup
@@ -27,7 +27,7 @@ jobs:
     name: PHPStan
     steps:
     - name: Checkout
-      uses: actions/checkout@v2
+      uses: actions/checkout@v5
 
     - name: Setup
       uses: ./.github/actions/setup
@@ -50,7 +50,7 @@ jobs:
     name: Test on PHP ${{ matrix.php-version }} ${{ matrix.composer-flags }}
     steps:
     - name: Checkout
-      uses: actions/checkout@v2
+      uses: actions/checkout@v5
 
     - name: Setup
       uses: ./.github/actions/setup