Update dependency org.apache.maven:maven-core to v3.8.7 (#7551)

Co-authored-by: Nrenovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

.gitpod/Dockerfile

 FROM gitpod/workspace-full
 
-ARG MAVEN_VERSION=3.8.6
+ARG MAVEN_VERSION=3.8.7
 
 RUN brew install gh && \
     bash -c ". /home/gitpod/.sdkman/bin/sdkman-init.sh && sdk install maven ${MAVEN_VERSION} && sdk default maven ${MAVEN_VERSION}"