build(deps): Bump NuGet.Protocol from 6.5.0 to 6.6.1 (#727)

Bumps [NuGet.Protocol](https://github.com/NuGet/NuGet.Client) from 6.5.0 to 6.6.1.
- [Release notes](https://github.com/NuGet/NuGet.Client/releases)
- [Commits](https://github.com/NuGet/NuGet.Client/commits)

---
updated-dependencies:
- dependency-name: NuGet.Protocol
  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>

Author: dependabot[bot]

winforms/demo/ReactiveDemo/ReactiveUIDemo.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
 	<PropertyGroup>
 		<TargetFramework>net6.0-windows10.0.17763.0</TargetFramework>
@@ -9,7 +9,7 @@
 
   <ItemGroup>
     <PackageReference Include="nuget.client" Version="4.2.0" />
-    <PackageReference Include="nuget.protocol" Version="6.5.0" />
+    <PackageReference Include="nuget.protocol" Version="6.6.1" />
     <PackageReference Include="ReactiveUI.WinForms" Version="18.*" />
   </ItemGroup>
 </Project>

wpf/getting-started/ReactiveDemo/ReactiveDemo.csproj

@@ -8,7 +8,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="NuGet.Protocol" Version="6.5.1" />
+    <PackageReference Include="NuGet.Protocol" Version="6.6.1" />
     <PackageReference Include="ReactiveUI.WPF" Version="18.*" />
   </ItemGroup>
 </Project>