Use checkout v3 to suppress action warning

.github/workflows/build.yaml

@@ -15,7 +15,7 @@ jobs:
         ]
         swift-version: [5.0]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: 2.7.4

.github/workflows/documentation.yaml

@@ -15,7 +15,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v1
+        uses: actions/checkout@v3
       - name: Generate Documentation
         uses: SwiftDocOrg/swift-doc@master
         with: