Bump NETStandard.Library from 2.0.0 to 2.0.3

Bumps [NETStandard.Library](https://github.com/dotnet/standard) from 2.0.0 to 2.0.3.
- [Release notes](https://github.com/dotnet/standard/releases)
- [Commits](dotnet/standard@v2.0.0...v2.0.3)

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

UWP.Build.targets

@@ -1,6 +1,6 @@
 <Project>
   <ItemGroup Condition="'$(TargetFramework)' == 'uap10.0.14393' AND  '$(OS)' == 'Windows_NT' ">
-    <PackageReference Include="NETStandard.Library" Version="2.0.1" />
+    <PackageReference Include="NETStandard.Library" Version="2.0.3" />
   </ItemGroup>
   <ItemGroup Condition="$(TargetFramework.StartsWith('uap10.0')) AND  '$(OS)' == 'Windows_NT' ">
     <SDKReference Include="WindowsMobile, Version=10.0.18362.0">