ci: add restore-keys to the maven-verify Maven cache

The lint and spotbugs jobs fall back to a restore-key prefix on a pom.xml
change; maven-verify lacked it, so any pom change gave it a hard cache miss and
a full ~/.m2 re-download. Add the same restore-keys for parity across all three
Maven jobs.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: joaodinissf

.github/workflows/verify.yml

@@ -201,6 +201,7 @@ jobs:
         with:
           path: /home/runner/.m2/repository
           key: ${{ runner.os }}-maven-0-${{ hashFiles('**/pom.xml') }}
+          restore-keys: ${{ runner.os }}-maven-0-
       - name: Build with Maven  within a virtual X Server Environment
         run: xvfb-run mvn clean verify -f ./ddk-parent/pom.xml --batch-mode --fail-at-end
       - name: Fail on missing surefire reports