Bump FsUnit.xUnit from 5.1.0 to 5.4.0

Bumps [FsUnit.xUnit](https://github.com/fsprojects/FsUnit) from 5.1.0 to 5.4.0.
- [Release notes](https://github.com/fsprojects/FsUnit/releases)
- [Changelog](https://github.com/fsprojects/FsUnit/blob/master/RELEASE_NOTES.md)
- [Commits](fsprojects/FsUnit@5.1.0...5.4.0)

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

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

src/FSharp.Control.TaskSeq.SmokeTests/FSharp.Control.TaskSeq.SmokeTests.fsproj

@@ -14,7 +14,7 @@
 
   <ItemGroup>
     <PackageReference Include="FSharp.Control.TaskSeq" Version="0.4.0-alpha.1" />
-    <PackageReference Include="FsUnit.xUnit" Version="5.1.0" />
+    <PackageReference Include="FsUnit.xUnit" Version="5.4.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.6.1" />
     <PackageReference Include="xunit" Version="2.5.0" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.5.0">

src/FSharp.Control.TaskSeq.Test/FSharp.Control.TaskSeq.Test.fsproj

@@ -56,7 +56,7 @@
     <!-- we use 6.0.3 here and not 6.0.2 because TaskResult lib requires it-->
     <PackageReference Update="FSharp.Core" Version="6.0.3" />
     <PackageReference Include="FsToolkit.ErrorHandling.TaskResult" Version="3.2.0" />
-    <PackageReference Include="FsUnit.xUnit" Version="5.1.0" />
+    <PackageReference Include="FsUnit.xUnit" Version="5.4.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.6.1" />
     <PackageReference Include="xunit" Version="2.5.0" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.5.0">