Bump test dependencies

Author: gitfool

Source/Cake.DotNetTool.Module.Tests/Cake.DotNetTool.Module.Tests.csproj

@@ -7,10 +7,10 @@
   <ItemGroup>
     <PackageReference Include="Cake.Core" Version="0.33.0" PrivateAssets="All" />
     <PackageReference Include="Cake.Testing" Version="0.33.0" PrivateAssets="All" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.6.0" />
-    <PackageReference Include="xunit" Version="2.3.1" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.3.1" />
-    <PackageReference Include="NSubstitute" Version="3.1.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.0.1" />
+    <PackageReference Include="xunit" Version="2.4.1" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.1" />
+    <PackageReference Include="NSubstitute" Version="4.0.0" />
   </ItemGroup>
 
   <ItemGroup>