Update GHA checkout actions to v3

v2 uses node v12, a deprecated version

.github/workflows/build.yml

@@ -13,7 +13,7 @@ jobs:
         image: redis:7.0.12-alpine  # Docker Hub image used as a sidecar
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Install dependencies
       run: |
         apt-get -y update

.github/workflows/codeql.yml

@@ -20,7 +20,7 @@ jobs:
 
     steps:
     - name: Check out repository
-      uses: actions/checkout@v2
+      uses: actions/checkout@v3
 
     - name: Initialize CodeQL
       uses: github/codeql-action/init@v2