Update distlib vendor library

[lambdaclan]

Description

Update distlib library from 0.2.4.dev0 to 0.2.9.post0. This
is necessary in order to be able to enforce Wheel distribution
based installations.

Relates # (PRs)
rez #602 , #628

Type of change

• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Remarks

• This should be merged once [WIP] Feature/pip install modern #602 is fully merged. Both [WIP] Feature/pip install modern #602 and [Feature] Pure python package detection #628 require a newer version of distlib libary in order to work. This distlib version provides a different API as such merging this first before Wheel distribution installation is enforced will cause errors. For example the allow_fail in

for installed_file in distribution.list_installed_files(allow_fail=True)

is no longer available.

[JeanChristopheMorinRodeoFX]

@lambdaclan could you update the vendor README please? Apart from that, I don't have much to say. 👍