Merge pull request #20557 from dotnet/updatenugetmoniker

Change nuget moniker for dev15.3.x to beta4

build/Targets/Versions.props

@@ -15,7 +15,7 @@
     <!-- The release moniker for our packages.  Developers should use "dev" and official builds pick the branch
          moniker listed below -->
     <RoslynNuGetMoniker Condition="'$(RoslynNuGetMoniker)' == ''">dev</RoslynNuGetMoniker>
-    <RoslynNuGetMoniker Condition="'$(OfficialBuild)' == 'true'">beta3</RoslynNuGetMoniker>
+    <RoslynNuGetMoniker Condition="'$(OfficialBuild)' == 'true'">beta4</RoslynNuGetMoniker>
     <!-- This is the base of the NuGet versioning for prerelease packages -->
     <NuGetPreReleaseVersion>$(RoslynFileVersionBase)-$(RoslynNuGetMoniker)</NuGetPreReleaseVersion>