Prepare Release Notes for v12

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 64.28%. Comparing base (5c6809d) to head (b266524).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #499 +/- ## ========================================== + Coverage 64.26% 64.28% +0.02% ========================================== Files 31 31 Lines 53579 53579 Branches 3905 3905 ========================================== + Hits 34430 34444 +14 + Misses 18989 18972 -17 - Partials 160 163 +3 ``` | [Flag](https://app.codecov.io/gh/dropbox/dropbox-sdk-python/pull/499/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dropbox) | Coverage Δ | | |---|---|---| | [integration](https://app.codecov.io/gh/dropbox/dropbox-sdk-python/pull/499/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dropbox) | `64.19% <ø> (+0.02%)` | :arrow_up: | | [unit](https://app.codecov.io/gh/dropbox/dropbox-sdk-python/pull/499/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dropbox) | `63.70% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dropbox#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[april]

LGTM