Update UAP version. (#155)

As we only support 15063 and above we can set the min target on the react native plugin. 

It also looks like a SDK version update was missing.

Author: nickwinder

windows/ReactNativePSPDFKit/ReactNativePSPDFKit/ReactNativePSPDFKit.csproj

@@ -12,7 +12,7 @@
     <DefaultLanguage>en-US</DefaultLanguage>
     <TargetPlatformIdentifier>UAP</TargetPlatformIdentifier>
     <TargetPlatformVersion Condition=" '$(TargetPlatformVersion)' == '' ">10.0.16299.0</TargetPlatformVersion>
-    <TargetPlatformMinVersion>10.0.10240.0</TargetPlatformMinVersion>
+    <TargetPlatformMinVersion>10.0.15063.0</TargetPlatformMinVersion>
     <MinimumVisualStudioVersion>14</MinimumVisualStudioVersion>
     <FileAlignment>512</FileAlignment>
     <ProjectTypeGuids>{A5A43C5B-DE2A-4C0C-9213-0A381AF9435A};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>