Added release dates to release notes.
Fixed #23701 -- Removed an unneeded check in collectstatic.

Thanks prathik for the report.
Added stub release notes for 1.7.2.
Fixed #23621 -- Warn for duplicate models when a module is reloaded.

Previously a RuntimeError was raised every time two models clashed
in the app registry. This prevented reloading a module in a REPL;
while it's not recommended to do so, we decided not to forbid this
use-case by turning the error into a warning.

Thanks @dfunckt and Sergey Pashinin for the initial patches.
Improved warning message when reloading models. Refs #23621.

Thanks dfunckt and Tim Graham.
Allowed test from refs #23612 to be run from a directory other than tests.
Fixed flake8 warning.
Made a doctest compatible with Python 2

That test might not always execute, but can be executed when the
parent test label is explicitely given.