Bump dependencies to final 6.0.0-preview3

And remove daily build feeds

Author: roji

Directory.Packages.props

@@ -1,8 +1,8 @@
 <Project>
   <PropertyGroup>
-    <EFCoreVersion>6.0.0-preview.3.21180.1</EFCoreVersion>
-    <MicrosoftExtensionsVersion>6.0.0-preview.3.21180.7</MicrosoftExtensionsVersion>
-    <NpgsqlVersion>6.0.0-ci.20210330T211505</NpgsqlVersion>
+    <EFCoreVersion>6.0.0-preview.3.21201.2</EFCoreVersion>
+    <MicrosoftExtensionsVersion>6.0.0-preview.3.21201.4</MicrosoftExtensionsVersion>
+    <NpgsqlVersion>6.0.0-preview3</NpgsqlVersion>
   </PropertyGroup>
 
   <ItemGroup>

NuGet.config

@@ -1,8 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <configuration>
     <packageSources>
-        <add key="dotnet6" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet6/nuget/v3/index.json" />
         <add key="nuget.org" value="https://api.nuget.org/v3/index.json" />
-        <add key="npgsql" value="https://www.myget.org/F/npgsql-unstable/api/v3/index.json" />
     </packageSources>
 </configuration>