change jdk version and add maven in action

.gitea/workflows/maven.yaml

@@ -1,20 +1,24 @@
 name: Gitea Actions Maven Build
 
 on:
-    push:
-        branches: ['master']
+  push:
+    branches: ['master']
 
 jobs:
-    build:
-        runs-on: ubuntu-latest
-        steps:
-          - name: Checkout the repo
-            uses: actions/checkout@v4
-          - name: Setup JDK 21
-            uses: actions/setup-java@v4
-            with:
-               java-version: 21
-               distribution: 'temurin'
-               cache: maven
-          - name: Build with Maven
-            run: mvn -B package --file pom.xml
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout the repo
+        uses: actions/checkout@v4
+      - name: Set up Maven
+        uses: stCarolas/setup-maven@v5
+        with:
+          maven-version: '3.8.2'
+      - name: Set up JDK 23
+        uses: actions/setup-java@v4
+        with:
+          java-version: 23
+          distribution: 'temurin'
+          cache: maven
+      - name: Build with Maven
+        run: mvn -B package --file pom.xml