build(deps): bump FluentAssertions from 6.9.0 to 6.12.0 in /src

Bumps [FluentAssertions](https://github.com/fluentassertions/fluentassertions) from 6.9.0 to 6.12.0.
- [Release notes](https://github.com/fluentassertions/fluentassertions/releases)
- [Changelog](https://github.com/fluentassertions/fluentassertions/blob/develop/AcceptApiChanges.ps1)
- [Commits](fluentassertions/fluentassertions@6.9.0...6.12.0)

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

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

src/Pharmacist.Tests/Pharmacist.Tests.csproj

@@ -29,7 +29,7 @@
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.5" />
     <PackageReference Include="Xunit.StaFact" Version="1.1.11" />
     <PackageReference Include="DiffEngine" Version="11.1.0" />
-    <PackageReference Include="FluentAssertions" Version="6.9.0" />
+    <PackageReference Include="FluentAssertions" Version="6.12.0" />
     <PackageReference Include="Microsoft.Reactive.Testing" Version="5.0.0" />
     <PackageReference Include="PublicApiGenerator" Version="10.3.0" />
     <PackageReference Include="Xamarin.Forms" Version="5.0.0.2545" />