chore(deps): update dependency nunit to v4 (#1058)

* chore(deps): update dependency nunit to v4

* chore(deps): update dependency snapshooter.nunit to v0.14.0

* chore: fix tests for .NET 4.6.2

---------

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: Florian Greinacher <[email protected]>

Author: renovate[bot]

tests/TestableIO.System.IO.Abstractions.TestingHelpers.Tests/TestableIO.System.IO.Abstractions.TestingHelpers.Tests.csproj

@@ -34,7 +34,7 @@
     <PackageReference Include="GitHubActionsTestLogger" Version="2.3.3" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
     <PackageReference Include="Moq" Version="4.20.70" />
-    <PackageReference Include="NUnit" Version="3.14.0" />
+    <PackageReference Include="NUnit" Version="4.0.1" />
     <PackageReference Include="NUnit.Analyzers" Version="3.10.0">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>

tests/TestableIO.System.IO.Abstractions.Wrappers.Tests/TestableIO.System.IO.Abstractions.Wrappers.Tests.csproj

@@ -19,15 +19,25 @@
     <PackageReference Include="GitHubActionsTestLogger" Version="2.3.3" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
     <PackageReference Include="Moq" Version="4.20.70" />
-    <PackageReference Include="NUnit" Version="3.14.0" />
+    <PackageReference Include="NUnit" Version="4.0.1" />
     <PackageReference Include="NUnit.Analyzers" Version="3.10.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="4.5.0" />
-    <PackageReference Include="Snapshooter.NUnit" Version="0.13.0" />
+    <PackageReference Include="Snapshooter.NUnit" Version="0.14.0" />
   </ItemGroup>
   <PropertyGroup>
     <!--
       Allow deprecated binary formatter functionality on .NET 8 so that we can test it
     -->
     <EnableUnsafeBinaryFormatterSerialization Condition="'$(TargetFramework)' == 'net8.0'">true</EnableUnsafeBinaryFormatterSerialization>
   </PropertyGroup>
+  <!--
+    Snapshooter is currently broken when referencing NUnit 4 from a .NET 4.6.2 project.
+    The following blocks work around this by referencing NUnit 3 in that case.
+  -->
+  <PropertyGroup>
+    <_Net462NUnitVersion>3.14.0</_Net462NUnitVersion>
+  </PropertyGroup>
+  <ItemGroup Condition="'$(TargetFramework)' == 'net462'">
+    <PackageReference Update="NUnit" Version="$(_Net462NUnitVersion)" />
+  </ItemGroup>
 </Project>