Add dependabot (#208)

.github/dependabot.yml

@@ -0,0 +1,10 @@
+# Dependabot config
+
+version: 2
+updates:
+- package-ecosystem: "maven"
+  directory: "/"
+  schedule:
+    interval: weekly
+    time: "02:30"
+  open-pull-requests-limit: 20

.github/workflows/build.yml

@@ -16,32 +16,30 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java: [1.8, 11]
+        java: [8, 11]
 
     steps:
+    - name: Checkout
+      uses: actions/checkout@2541b1294d2704b0964813337f33b291d3f8596b  #v3.0.2
+
     - name: Set up JDK
-      uses: actions/setup-java@v1
+      uses: actions/setup-java@2c7a4878f5d120bd643426d54ae1209b29cc01a3  #v3.4.1
       with:
         java-version: ${{ matrix.java }}
-    - name: Checkout
-      uses: actions/checkout@v2
-    - name: Maven cache
-      uses: actions/cache@v1
-      with:
-        path: ~/.m2/repository
-        key: ${{ runner.os }}-maven-${{ matrix.java }}-${{ hashFiles('**/pom.xml') }}-${{ hashFiles('.github/workflows/build.yml') }}
-        restore-keys: |
-          ${{ runner.os }}-maven-
+        distribution: 'temurin'
+        cache: 'maven'
+
     - name: Maven version
       run: |
         mkdir -p ./.mvn
         echo '-e -B -DtrimStackTrace=false' > ./.mvn/maven.config
         mvn --version
         mkdir -p target
+
     - name: Maven build
       run: |
         mvn install site
-    
+
     - name: Website
       if: matrix.java == '11' && github.event_name == 'push' && (startsWith(github.ref, 'refs/tags/website') || startsWith(github.ref, 'refs/tags/v'))
       env: