Bump xunit from 2.4.2 to 2.7.0 (#126)

* Bump xunit from 2.4.2 to 2.5.0

Bumps [xunit](https://github.com/xunit/xunit) from 2.4.2 to 2.5.0.
- [Commits](xunit/xunit@2.4.2...2.5.0)

---
updated-dependencies:
- dependency-name: xunit
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

* Fix compiler errors.

xUnit's `Assert.NotNull` now supports nullable annotations. We don't need to throw `NotNullException` which for some reason cannot be found in the new version.

* Update xunit to version 2.7.0.

Hooray, it explicitly targets .NET Standard 2.0! 🎉

---------

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Theodore Tsirpanis <[email protected]>

Directory.Packages.props

@@ -42,8 +42,8 @@
     <PackageVersion Include="System.Memory" Version="4.5.5" />
     <PackageVersion Include="System.Reflection.MetadataLoadContext" Version="8.0.0" />
     <PackageVersion Include="System.Threading.Tasks.Extensions" Version="4.5.4" />
-    <PackageVersion Include="xunit.runner.visualstudio" Version="2.5.4" />
-    <PackageVersion Include="xunit" Version="2.4.2" />
+    <PackageVersion Include="xunit" Version="2.7.0" />
+    <PackageVersion Include="xunit.runner.visualstudio" Version="2.5.7" />
     <PackageVersion Include="YoloDev.Expecto.TestSdk" Version="0.14.3" />
 
     <PackageVersion Include="Fake.Api.GitHub" Version="$(FakeVersion)" />

tests/Farkle.Tools.MSBuild.Tests/PrecompiledGrammarEquivalenceTests.cs

@@ -51,8 +51,8 @@ public void Check_Precompiled_Grammar_Equivalence(string fieldName)
             if (pcdf == null)
                 throw new MissingFieldException(typeof(PrecompilableDesigntimeFarkle).FullName, fieldName);
 
-            var precompiledGrammar =
-                pcdf.TryGetPrecompiledGrammar()?.Value.GetGrammar() ?? throw new NotNullException();
+            var precompiledGrammar = pcdf.TryGetPrecompiledGrammar()?.Value.GetGrammar();
+            Assert.NotNull(precompiledGrammar);
             var builtGrammar = pcdf.InnerDesigntimeFarkle.BuildUntyped().GetGrammar();
 
             Assert.Equal(GrammarSource.Precompiled, precompiledGrammar.Properties.Source);