Updating BuildTools from 2.1.3-rtm-15819 to 2.1.3-rtm-15820
Updating BuildTools from 2.1.3-rtm-15819 to 2.1.3-rtm-15820

[auto-updated: buildtools]

aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore