Merge pull request #138 from apache/dependabot/github_actions/actions/checkout-v2.3.1

Bump actions/checkout from v1 to v2.3.1
diff --git a/.github/workflows/maven.yml b/.github/workflows/maven.yml
index 7b9b8ed..d2a0dbc 100644
--- a/.github/workflows/maven.yml
+++ b/.github/workflows/maven.yml
@@ -33,7 +33,7 @@
             experimental: true
         
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2.3.1
     - name: Set up JDK ${{ matrix.java }}
       uses: actions/setup-java@v1.4.0
       with: