fix: use Java 11 in CodeQL workflow, matching project source/target level

The project compiles at source/target 11 (pom.xml), so Java 8 was
already wrong regardless of the plugin issue. Java 11 is the minimum
that can build this project and also satisfies the git-commit-id-maven-
plugin:10.0.0 Java >= 11 prerequisite.

Author: bernardladenthin

.github/workflows/codeql.yml

@@ -21,7 +21,7 @@ jobs:
     steps:
       - uses: actions/checkout@v6
       - uses: actions/setup-java@v5
-        with: { java-version: '21', distribution: temurin }
+        with: { java-version: '11', distribution: temurin }
       - uses: github/codeql-action/init@v4
         with: { languages: java, queries: +security-and-quality }
       - name: Build with Maven