build: configure maven compiler

.gitea/workflows/build.yml

@@ -19,6 +19,19 @@ jobs:
         with:
           distribution: temurin
           java-version: 21
+          cache: maven
+
+      - name: Install Maven
+        run: |
+          if ! command -v mvn >/dev/null 2>&1; then
+            if command -v sudo >/dev/null 2>&1; then
+              sudo apt-get update
+              sudo apt-get install -y maven
+            else
+              apt-get update
+              apt-get install -y maven
+            fi
+          fi
 
       - name: Set up Node
         uses: actions/setup-node@v4

pom.xml

@@ -42,6 +42,14 @@
 
     <build>
         <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.11.0</version>
+                <configuration>
+                    <release>${maven.compiler.release}</release>
+                </configuration>
+            </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-shade-plugin</artifactId>