Bump to latest dotnet 3.1.x

Author: decriptor

.github/workflows/mac.yml

@@ -18,7 +18,7 @@ jobs:
     - name: Setup .NET Core
       uses: actions/setup-dotnet@v1
       with:
-        dotnet-version: 3.1.404
+        dotnet-version: 3.1.421
     - name: Build with dotnet
       run: dotnet build --configuration Release
     - name: Run unit tests

.github/workflows/ubuntu.yml

@@ -18,7 +18,7 @@ jobs:
     - name: Setup .NET Core
       uses: actions/setup-dotnet@v1
       with:
-        dotnet-version: 3.1.404
+        dotnet-version: 3.1.421
     - name: Build with dotnet
       run: dotnet build --configuration Release
     - name: Run unit tests

.github/workflows/windows.yml

@@ -18,7 +18,7 @@ jobs:
     - name: Setup .NET Core
       uses: actions/setup-dotnet@v1
       with:
-        dotnet-version: 3.1.404
+        dotnet-version: 3.1.421
 
     - name: Clean
       run: dotnet clean --configuration Release && dotnet nuget locals all --clear