ci: use JDK 25 for the release (#2188)

Author: zepfred

.github/workflows/release.yml

@@ -54,7 +54,7 @@ jobs:
 
       - uses: actions/setup-java@v5
         with:
-          java-version: '21'
+          java-version: '25'
           distribution: 'temurin'
           cache: 'maven'
 

CONTRIBUTING.md

@@ -78,7 +78,7 @@ Use one of the following ways to build this project:
 - 🚀 **build-fast**: `./mvnw clean install -Dquickly` - Skips checks and code analysis (~1 min)
 - 🔨 **build-normally**: `./mvnw clean install` - Runs tests, checks code style, skips documentation (~17 min)
 - 📄 **build-doc**: `./mvnw clean install` in the `docs` directory - Creates asciidoctor documentation `docs/target/html_single/index.html` (~2 min)
-- 🦾 **build-all**: `./mvnw clean install -Dfull` - Runs all checks, creates documentation and distribution files (~20 min)
+- 🦾 **build-all**: `./mvnw clean install -Dfull` - Runs all checks, creates documentation and distribution files (~20 min). It requires JDK 25+ to build properly.
 
 ---
 
@@ -129,4 +129,4 @@ PRs that worsen grades below B will fail CI and cannot be merged.
 - All code must have tests before being merged
 - Use **JUnit** for test execution
 - Use **AssertJ** for all assertions (JUnit assertions are forbidden)
-- Mockito allowed for mocking; prefer real objects when practical
+- Mockito allowed for mocking; prefer real objects when practical