Update GitHub Actions checkout to v3 (#1390)

.github/workflows/build.yml

@@ -18,7 +18,7 @@ jobs:
 
     steps:
     - name: Checkout source code
-      uses: actions/checkout@v2
+      uses: actions/checkout@v3
 
     - name: Test
       run: dotnet test --configuration Release --logger GitHubActions

.github/workflows/pr.yml

@@ -15,7 +15,7 @@ jobs:
 
     steps:
     - name: Checkout source code
-      uses: actions/checkout@v2
+      uses: actions/checkout@v3
 
     - name: Test
       run: dotnet test --configuration Release --logger GitHubActions
@@ -28,7 +28,7 @@ jobs:
 
     steps:
     - name: Checkout source code
-      uses: actions/checkout@v2
+      uses: actions/checkout@v3
 
     - name: Test
       run: dotnet test --configuration Release --logger GitHubActions

.github/workflows/release.yml

@@ -15,7 +15,7 @@ jobs:
 
     steps:
     - name: Checkout source code
-      uses: actions/checkout@v2
+      uses: actions/checkout@v3
 
     - name: Test
       run: dotnet test --configuration Release --logger GitHubActions