Bump Fody from 6.6.4 to 6.8.0

Bumps [Fody](https://github.com/Fody/Fody) from 6.6.4 to 6.8.0.
- [Release notes](https://github.com/Fody/Fody/releases)
- [Commits](Fody/Fody@6.6.4...6.8.0)

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

Signed-off-by: dependabot[bot] <support@github.com>

src/StructLinq/StructLinq.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
  <PropertyGroup>
  <TargetFrameworks>netstandard1.1;net452;net472;net48;netcoreapp2.1;netcoreapp2.2;netcoreapp3.0;netcoreapp3.1;net50;net60;net70</TargetFrameworks>
@@ -13,7 +13,7 @@
  </PropertyGroup>
 
  <ItemGroup>
- <PackageReference Include="Fody" Version="6.6.4">
+ <PackageReference Include="Fody" Version="6.8.0">
  <PrivateAssets>all</PrivateAssets>
  <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
  </PackageReference>