(deps): Bump xunit.assert from 2.8.0 to 2.8.1 in /build

Bumps xunit.assert from 2.8.0 to 2.8.1.

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

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

Author: dependabot[bot]

build/Directory.Packages.props

@@ -14,6 +14,6 @@
     <PackageVersion Include="Cake.Docker" Version="1.3.0" />
     <PackageVersion Include="Cake.Json" Version="7.0.1" />
     <PackageVersion Include="Cake.Wyam" Version="2.2.14" />
-    <PackageVersion Include="xunit.assert" Version="2.8.0" />
+    <PackageVersion Include="xunit.assert" Version="2.8.1" />
   </ItemGroup>
 </Project>