(maint) Fix Chocolatey solution filter

There was a typo in one of the projects used for the solution filter,
which causes all builds to fail when the filter is being used.

This commit fixes this by adding the missing 's' to the
project folder name.

Chocolatey-NuGet.slnf

@@ -13,7 +13,7 @@
             "src\\NuGet.Core\\NuGet.ProjectModel\\NuGet.ProjectModel.csproj",
             "src\\NuGet.Core\\NuGet.Resolver\\NuGet.Resolver.csproj",
             "src\\NuGet.Core\\NuGet.Versioning\\NuGet.Versioning.csproj",
-            "src\\NuGet.Core\\NuGet.Credential\\NuGet.Credentials.csproj",
+            "src\\NuGet.Core\\NuGet.Credentials\\NuGet.Credentials.csproj",
             "src\\NuGet.Core\\NuGet.LibraryModel\\NuGet.LibraryModel.csproj",
             "test\\NuGet.Core.Tests\\NuGet.Commands.Test\\NuGet.Commands.Test.csproj",
             "test\\NuGet.Core.Tests\\NuGet.Common.Test\\NuGet.Common.Test.csproj",
@@ -35,4 +35,4 @@
             "test\\TestUtilities\\Test.Utility\\Test.Utility.csproj"
         ]
     }
-}
+}