publish azure identity 0.12.0 for azcore alignment

[baywet]

Bug Report

At time of writing:
azcore 0.20.0
azidentity 0.11.0 -> azcore 0.19.0

This becomes an issue if you have a transitive dependency on azcore 0.20.0 and an direct dependency on azidentity 0.11.0 as it seems that azcore 0.20.0 breaks a bunch of APIs (see #15886).

Releasing azidentity 0.12.0 since the alignment work in the code is already done would solve the problem.

[chlowell]

azidentity 0.12.0, which requires azcore 0.20.0, is available now. There are a number of API changes, detailed in the changelog, so you may need to update your code, depending on which credentials you use. Please open another issue if you find something that doesn't work.

[baywet]

Thanks for the quick turnaround on this one!