Mock v2.13 release

[Pavel Raiskup]

Hello!

I'm glad I can announce that we have a new release of Mock.  Two new
commandline options were added, and several bugs were fixed.  For more
info see the upstream release notes:

https://rpm-software-management.github.io/mock/Release-Notes-2.13

Note that this release is likely the last v2 release being shipped both in
Fedora 33+ and EPEL 7+.  We'll keep v2 in bugfix mode for the purpose of
EPEL 7 builds, and elsewhere we'll forward with v3.  For more info see:
https://github.com/rpm-software-management/mock/issues/755

Happy building!
Pavel