ci: use mvn verify phase instead of install

Installing the artifacts is not necessary, and
currently we have to remove them from the build
cache to prevent that from growing too large

.github/workflows/CI.yml

@@ -27,6 +27,3 @@ jobs:
 
       - name: Build
         run: ./ci/build.sh
-
-      - name: Remove build artifacts
-        run: rm -rf ~/.m2/repository/net/runelite