prepare release 2021.11b1 (psf#2622)

prepare release 21.11b0 (psf#2616)

Update CHANGES.md for 21.10b0 release (psf#2583)

* Update CHANGES.md for 21.10b0 release

* Update version in docs/usage_and_configuration/the_basics.md

* Also update docs/integrations/source_version_control.md ...

Update CHANGES.md for 21.10b0 release (psf#2583)

* Update CHANGES.md for 21.10b0 release

* Update version in docs/usage_and_configuration/the_basics.md

* Also update docs/integrations/source_version_control.md ...

Update CHANGES.md for 21.9b0 release (psf#2494)

Exclude broken typing-extensions version + fix import (psf#2460)

re. import, the ipynb code was assuming that typing-extensions would
always be available, but that's not the case! There's an environment
marker on the requirement meaning it won't get installed on 3.10 or
higher. The test suite didn't catch this issue since aiohttp pulls in
typing-extensions unconditionally.

Update CHANGES.md for 21.7b0 release (psf#2376)

* Update CHANGES.md for 21.7b0 release

* move some changes to the right section

* another one

Co-authored-by: Jelle Zijlstra <[email protected]>

Update CHANGES.md for 21.6b0 release (psf#2325)

Update CHANGES.md for 21.5b2 release (psf#2290)

* Update CHANGES.md for 21.5b2 release

fix typo (psf#2217)