build(deps): bump Fody from 6.3.0 to 6.4.0 in /src (#2703)

Bumps [Fody](https://github.com/Fody/Fody) from 6.3.0 to 6.4.0.
- [Release notes](https://github.com/Fody/Fody/releases)
- [Commits](https://github.com/Fody/Fody/commits/6.4.0)

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.Helpers/ReactiveUI.Fody.Helpers.csproj

@@ -17,7 +17,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Fody" Version="6.3.0" PrivateAssets="None" />
+    <PackageReference Include="Fody" Version="6.4.0" PrivateAssets="None" />
     <PackageReference Include="FodyPackaging" Version="6.3.0" PrivateAssets="All" />
     <PackageReference Include="System.Reactive" Version="5.0.0" />
   </ItemGroup>