actions: use java 21 in CI

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java: [ 17 ]
+        java: [ 21 ]
     steps:
       - uses: actions/checkout@v4
 

.github/workflows/docker-migrations-build-test.yml

@@ -15,10 +15,10 @@ jobs:
       - uses: actions/checkout@v4
         with:
           ref: ${{ github.event.pull_request.base.sha }}
-      - name: set up JDK 17
+      - name: set up JDK 21
         uses: actions/setup-java@v3
         with:
-          java-version: 17
+          java-version: 21
           distribution: temurin
           cache: "gradle"
       - name: Run Build

.github/workflows/fat-build.yml

@@ -9,10 +9,10 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - name: set up JDK 17
+      - name: set up JDK 21
         uses: actions/setup-java@v3
         with:
-          java-version: 17
+          java-version: 21
           distribution: temurin
           cache: "gradle"
       - name: Run Build