Use preview-GITHUB_RUN_NUMBER for MyGet feed version (#1132)

.github/workflows/build.yml

@@ -28,7 +28,7 @@ jobs:
       run: dotnet test --configuration Release --logger:"console;verbosity=quiet"
 
     - name: Pack with dotnet
-      run: dotnet pack --output artifacts --configuration Release -p:PackageVersion=$GITHUB_RUN_ID
+      run: dotnet pack --output artifacts --configuration Release -p:PackageVersion=3.0.0-preview-$GITHUB_RUN_NUMBER
 
     - name: Push with dotnet
       run: dotnet nuget push artifacts/*.nupkg --api-key ${{ secrets.MYGET_API_KEY }} --skip-duplicate --source https://www.myget.org/F/jint/api/v2/package