build(deps): bump FodyHelpers from 6.6.3 to 6.6.4 in /src (#3400)

Bumps [FodyHelpers](https://github.com/Fody/Fody) from 6.6.3 to 6.6.4.
- [Release notes](https://github.com/Fody/Fody/releases)
- [Commits](Fody/Fody@6.6.3...6.6.4)

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

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

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

Author: dependabot[bot]

src/ReactiveUI.Fody/ReactiveUI.Fody.csproj

@@ -8,6 +8,6 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="FodyHelpers" Version="6.6.3" />
+    <PackageReference Include="FodyHelpers" Version="6.6.4" />
   </ItemGroup>
 </Project>