Currently, pythoncapi_compat.h is distributed under the MIT license. To respect the license, if a project copies the pythoncapi_compat.h, the MIT license must be mentioned in the project. See immutables for a concrete example:

• pythoncapi_compat.h is MIT licensed MagicStack/immutables#64
• MagicStack/immutables@67c5edf
• 14c4ade

To maximize the usage of the pythoncapi_compat.h file, I propose the change the license from MIT to Zero-Clause BSD license also known as ""Free Public License 1.0.0": https://opensource.org/licenses/0BSD

This license doesn't require anything, there is no need to mention 0BSD in a project including a copy of pythoncapi_compat.h.

Examples of the Python documentation, like the compatibility code in What's New in Python 3.10 and 3.11, is under the "Zero Clause BSD License". See the bottom of https://docs.python.org/dev/whatsnew/3.11.html for example:

Examples, recipes, and other code in the documentation are additionally licensed under the Zero Clause BSD License.