Update NUnit from 3.14.0 to 4.1.0

Author: aristotelos

src/FlaUI.WebDriver.UITests/FlaUI.WebDriver.UITests.csproj

@@ -9,7 +9,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.9.0" />
-    <PackageReference Include="NUnit" Version="3.14.0" />
+    <PackageReference Include="NUnit" Version="4.1.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="4.5.0" />
     <PackageReference Include="Selenium.WebDriver" Version="4.20.0" />
     <PackageReference Include="coverlet.collector" Version="6.0.2">