Update the version to beta2

Author: xuzhg

tools/WebStack.versions.settings.targets

@@ -6,7 +6,7 @@
     <VersionMajor Condition="'$(VersionMajor)' == ''">7</VersionMajor>
     <VersionMinor Condition="'$(VersionMinor)' == ''">4</VersionMinor>
     <VersionBuild Condition="'$(VersionBuild)' == ''">0</VersionBuild>
-    <VersionRelease Condition="'$(VersionRelease)' == ''">beta</VersionRelease>
+    <VersionRelease Condition="'$(VersionRelease)' == ''">beta2</VersionRelease>
   </PropertyGroup>
 
   <!-- For NuGet Package Dependencies -->