[14.0] [FIX] fastapi: Compatibility with latest Odoo

[renda-dev]

Fixing tests for fastapi

• pin pydantic version in fastapi (not required for the repo, but mandatory for the module to work)
• update loading of middlewares according to https://github.com/encode/starlette/pull/2381
• pin fastapi starlette version in extendable_fastapi (otherwise it would break the tests)
• backport of https://github.com/OCA/rest-framework/pull/416

[OCA-git-bot]

Hi @lmignon, some modules you are maintaining are being modified, check this out!

[lmignon]

/ocabot merge major

[OCA-git-bot]

Hey, thanks for contributing! Proceeding to merge this for you. Prepared branch 14.0-ocabot-merge-pr-417-by-lmignon-bump-major, awaiting test results.

[OCA-git-bot]

Congratulations, your PR was merged at dfc9321032e9508182e4aff1f2e901dc1299a533. Thanks a lot for contributing to OCA. ❤️