Upgrade GitHub Actions actions/cache to v2

Author: superstructor

.github/workflows/continuous-deployment-workflow.yml

@@ -13,7 +13,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - name: Maven cache
-        uses: actions/cache@v1
+        uses: actions/cache@v2
         with:
           path: /root/.m2/repository
           key: ${{ runner.os }}-maven-${{ hashFiles('project.clj') }}