Pin GitHub Actions dependencies with commit SHAs and update dependabot config

Co-authored-by: scordio <[email protected]>

Author: Copilot

.github/dependabot.yml

@@ -7,4 +7,8 @@ updates:
   - package-ecosystem: "github-actions"
     directory: "/"
     schedule:
-      interval: "daily"
+      interval: "weekly"
+    groups:
+      github-actions:
+        patterns:
+          - "*"

.github/workflows/gradle-wrapper-validation.yml

@@ -6,5 +6,5 @@ jobs:
     name: "Validation"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
-      - uses: gradle/wrapper-validation-action@v3
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+      - uses: gradle/wrapper-validation-action@f9c9c575b8b21b6485636a91ffecd10e558c62f6 # v3.5.0

.github/workflows/main.yml

@@ -13,9 +13,9 @@ jobs:
     name: "Asciidoctor"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
       - name: Set up JDK 11
-        uses: actions/setup-java@v5
+        uses: actions/setup-java@dded0888837ed1f317902acf8a20df0ad188d165 # v5.0.0
         with:
           distribution: 'zulu'
           java-version: 11