Bump Bullseye from 4.2.0 to 4.2.1 in /build (#136)

Bumps [Bullseye](https://github.com/adamralph/bullseye) from 4.2.0 to 4.2.1.
- [Release notes](https://github.com/adamralph/bullseye/releases)
- [Changelog](https://github.com/adamralph/bullseye/blob/main/CHANGELOG.md)
- [Commits](adamralph/bullseye@4.2.0...4.2.1)

---
updated-dependencies:
- dependency-name: Bullseye
  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]

build/build.csproj

@@ -6,7 +6,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Bullseye" Version="4.2.0" />
+    <PackageReference Include="Bullseye" Version="4.2.1" />
     <PackageReference Include="SimpleExec" Version="11.0.0" />
     <PackageReference Include="System.Text.Json" Version="7.0.1" />
   </ItemGroup>