ci: bump Code format job to Java 17

The springai sample modules require Java 17 (Spring AI 1.1 needs
Spring Boot 3.x, which needs Java 17). Running spotlessCheck on
Java 11 made google-java-format choke on text blocks in those
sources with "unclosed string literal" errors. Bump the format
job's setup-java to 17 so it can parse the springai sources.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: donald-pinckney

.github/workflows/ci.yml

@@ -42,11 +42,14 @@ jobs:
     - name: Set up Java
       uses: actions/setup-java@be666c2fcd27ec809703dec50e508c2fdc7f6654 # v5
       with:
-        java-version: "11"
+        # The springai sample modules require Java 17 (Spring AI 1.1 needs
+        # Spring Boot 3.x, which needs Java 17). google-java-format has to
+        # run on Java 17 to parse those sources.
+        java-version: "17"
         distribution: "temurin"
 
     - name: Set up Gradle
       uses: gradle/actions/setup-gradle@ac396bf1a80af16236baf54bd7330ae21dc6ece5 # v6
-    
+
     - name: Run copyright and code format checks
       run: ./gradlew --no-daemon spotlessCheck