Revert "Remove AfterTargets to workaround xbuild bug"

This reverts commit 1c96771.
After this change, cloud build numbers were no longer set automatically.
I'm not sure why I thought this change was good without offering an
alternative way for these targets to be automatically invoked.

Fixes #110

Author: AArnott

src/Nerdbank.GitVersioning.NuGet/build/NerdBank.GitVersioning.targets

@@ -87,6 +87,7 @@
 
   <Target Name="SetCloudBuildVersionVars"
         DependsOnTargets="GetBuildVersion"
+        AfterTargets="GetBuildVersion"
         Condition=" '@(CloudBuildVersionVars)' != '' ">
     <Nerdbank.GitVersioning.Tasks.SetCloudBuildVariables
       CloudBuildVersionVars="@(CloudBuildVersionVars)">
@@ -99,6 +100,7 @@
 
   <Target Name="SetCloudBuildNumberWithVersion"
         DependsOnTargets="GetBuildVersion"
+        AfterTargets="GetBuildVersion"
         Condition=" '$(CloudBuildNumber)' != '' ">
     <Nerdbank.GitVersioning.Tasks.SetCloudBuildVariables
       CloudBuildNumber="$(CloudBuildNumber)">