bump setup-dotnet from v3 to v4

Author: jnyrup

.github/workflows/build.yml

@@ -16,7 +16,7 @@ jobs:
         fetch-depth: 0
 
     - name: Setup .NET SDKs
-      uses: actions/setup-dotnet@v3
+      uses: actions/setup-dotnet@v4
       with:
         dotnet-version: |
           2.1.x
@@ -60,7 +60,7 @@ jobs:
         fetch-depth: 0
 
     - name: Setup .NET SDKs
-      uses: actions/setup-dotnet@v3
+      uses: actions/setup-dotnet@v4
       with:
         dotnet-version: |
           2.1.x