(CONT-903) Use checkout@v3 in Kubernetes

Prior to this commit, there were deprecation warnings in the k8s CI. This is because K8s was using checkout@v2 rather than v3. This commit adds v3.

Author: GSPatton

.github/workflows/ci.yml

@@ -20,7 +20,7 @@ jobs:
 
     steps:
     - name: Checkout Source
-      uses: actions/checkout@v2
+      uses: actions/checkout@v3
 
     - name: Activate Ruby 2.7
       uses: ruby/setup-ruby@v1

.github/workflows/nightly.yml

@@ -18,7 +18,7 @@ jobs:
 
     steps:
     - name: Checkout Source
-      uses: actions/checkout@v2
+      uses: actions/checkout@v3
 
     - name: Activate Ruby 2.7
       uses: ruby/setup-ruby@v1