(deps): Bump xunit.assert from 2.9.0 to 2.9.1 in /build

Bumps [xunit.assert](https://github.com/xunit/xunit) from 2.9.0 to 2.9.1.
- [Commits](xunit/xunit@2.9.0...2.9.1)

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

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

Author: dependabot[bot]

build/Directory.Packages.props

@@ -15,6 +15,6 @@
     <PackageVersion Include="Cake.Json" Version="7.0.1" />
     <PackageVersion Include="Cake.Npx" Version="1.7.0" />
     <PackageVersion Include="Cake.Wyam" Version="2.2.14" />
-    <PackageVersion Include="xunit.assert" Version="2.9.0" />
+    <PackageVersion Include="xunit.assert" Version="2.9.1" />
   </ItemGroup>
 </Project>