Fix CS7035 warning in dependabot jobs (#2849)

Fix `CS7035` warnings from `$GITHUB_RUN_NUMBER` not being set when dependabot jobs run.

Author: martincostello

eng/Common.targets

@@ -25,10 +25,10 @@
 
   <Target Name="CustomizeVersions" AfterTargets="MinVer" Condition="'$(GITHUB_ACTIONS)' == 'true'">
     <PropertyGroup>
-      <FileVersion>$([MSBuild]::ValueOrDefault('$(MinVerMajor)', '8')).$([MSBuild]::ValueOrDefault('$(MinVerMinor)', '6')).$([MSBuild]::ValueOrDefault('$(MinVerPatch)', '0')).$(GITHUB_RUN_NUMBER)</FileVersion>
+      <FileVersion>$([MSBuild]::ValueOrDefault('$(MinVerMajor)', '8')).$([MSBuild]::ValueOrDefault('$(MinVerMinor)', '6')).$([MSBuild]::ValueOrDefault('$(MinVerPatch)', '0')).$([MSBuild]::ValueOrDefault('$(GITHUB_RUN_NUMBER)', '0'))</FileVersion>
     </PropertyGroup>
     <PropertyGroup Condition="$(GITHUB_REF.StartsWith(`refs/pull/`))">
-      <PackageVersion>$(MinVerMajor).$(MinVerMinor).$(MinVerPatch)-pr.$(GITHUB_REF_NAME.Replace(`/merge`, ``)).$(GITHUB_RUN_NUMBER)</PackageVersion>
+      <PackageVersion>$(MinVerMajor).$(MinVerMinor).$(MinVerPatch)-pr.$(GITHUB_REF_NAME.Replace(`/merge`, ``)).$([MSBuild]::ValueOrDefault('$(GITHUB_RUN_NUMBER)', '0'))</PackageVersion>
     </PropertyGroup>
   </Target>