Bump bunit from 1.5.12 to 1.6.4 in /src (#337)

Bumps [bunit](https://github.com/bUnit-dev/bUnit) from 1.5.12 to 1.6.4.
- [Release notes](https://github.com/bUnit-dev/bUnit/releases)
- [Changelog](https://github.com/bUnit-dev/bUnit/blob/main/CHANGELOG.md)
- [Commits](bUnit-dev/bUnit@v1.5.12...v1.6.4)

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

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

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

src/AzureIoTHub.Portal.Server.Tests.Unit/AzureIoTHub.Portal.Server.Tests.Unit.csproj

@@ -7,10 +7,10 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="bunit" Version="1.5.12" />
+    <PackageReference Include="bunit" Version="1.6.4" />
     <PackageReference Include="bunit.core" Version="1.6.4" />
-    <PackageReference Include="bunit.web" Version="1.5.12" />
-    <PackageReference Include="bunit.web.testcomponents" Version="1.5.12" />
+    <PackageReference Include="bunit.web" Version="1.6.4" />
+    <PackageReference Include="bunit.web.testcomponents" Version="1.6.4" />
     <PackageReference Include="FluentAssertions" Version="6.5.1" />
     <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="6.0.2" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.1.0" />