Upgrade checkout and upload-artifact actions to v4.

Author: KubaSzostak

.github/workflows/dotnet.yml

@@ -13,7 +13,7 @@ jobs:
 
     steps:
     - name: Get source
-      uses: actions/checkout@v2
+      uses: actions/checkout@v4
 
     - name: Setup .NET 6.0
       uses: actions/setup-dotnet@v4
@@ -31,7 +31,7 @@ jobs:
       run: dotnet pack -c Release --no-build -o artifacts -p:NoWarn=NU5105
 
     - name: Upload
-      uses: actions/upload-artifact@v2
+      uses: actions/upload-artifact@v4
       with:
         name: NuGet Package Files (${{ matrix.os }})
         path: artifacts