Update dependabot.yml

Author: dhilpipre

.github/workflows/dependabot.yml

@@ -13,7 +13,7 @@ jobs:
     - name: Set up JDK 8
       uses: actions/setup-java@v1
       with:
-          java-version: 8
+          java-version: 9
     - name: Setup libraries
       run: | 
           ./newrelic-dependencies.sh