Bump Akka.TestKit.XUnit2 from 1.5.1 to 1.5.4 (#204)

Bumps [Akka.TestKit.XUnit2](https://github.com/akkadotnet/akka.net) from 1.5.1 to 1.5.4.
- [Release notes](https://github.com/akkadotnet/akka.net/releases)
- [Changelog](https://github.com/akkadotnet/akka.net/blob/dev/RELEASE_NOTES.md)
- [Commits](akkadotnet/akka.net@1.5.1...1.5.4)

---
updated-dependencies:
- dependency-name: Akka.TestKit.XUnit2
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

src/Directory.Packages.props

@@ -42,6 +42,6 @@
     <PackageVersion Include="xunit.runner.visualstudio" Version="2.4.5" />
     <PackageVersion Include="FluentAssertions" Version="6.10.0" />
     <PackageVersion Include="coverlet.collector" Version="3.2.0" />
-    <PackageVersion Include="Akka.TestKit.XUnit2" Version="1.5.1" />
+    <PackageVersion Include="Akka.TestKit.XUnit2" Version="1.5.4" />
   </ItemGroup>
 </Project>