Fix NuGet.config

EFCore.PG.sln

@@ -8,6 +8,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution
 		Directory.Build.props = Directory.Build.props
 		Directory.Packages.props = Directory.Packages.props
 		README.md = README.md
+		NuGet.config = NuGet.config
 	EndProjectSection
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{8537E50E-CF7F-49CB-B4EF-3E2A1B11F050}"

NuGet.config

@@ -1,35 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <configuration>
     <packageSources>
-        <add key="dotnet7" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet7/nuget/v3/index.json" />
-        <add key="dotnet-eng" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-eng/nuget/v3/index.json" />
-        <add key="npgsql-vnext" value="https://www.myget.org/F/npgsql-vnext/api/v3/index.json" />
+        <clear />
         <add key="nuget.org" value="https://api.nuget.org/v3/index.json" />
     </packageSources>
-
-    <packageSourceMapping>
-        <packageSource key="nuget.org">
-            <package pattern="*" />
-            <!-- Our npgsql-vnext feed doesn't necessarily contain the last preview (package retention rules...), so we take it from nuget.org -->
-            <package pattern="Npgsql" />
-            <package pattern="Npgsql.*" />
-        </packageSource>
-        <packageSource key="npgsql-vnext">
-            <package pattern="Npgsql" />
-            <package pattern="Npgsql.*" />
-        </packageSource>
-        <packageSource key="dotnet7">
-            <package pattern="*" />
-        </packageSource>
-        <packageSource key="dotnet-eng">
-            <!-- EF Core depends on xunit 2.4.2-pre.9 which is only in dotnet-eng.
-                 But some xunit packages still need to come from nuget.org, so we cherry-pick. -->
-            <package pattern="xunit" />
-            <package pattern="xunit.assert" />
-            <package pattern="xunit.core" />
-            <package pattern="xunit.extensibility.core" />
-            <package pattern="xunit.extensibility.execution" />
-        </packageSource>
-    </packageSourceMapping>
-
 </configuration>