Added OAuth 2.0 PKCE support

Hello!

This adds support for OAuth 2.0 PKCE.

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v2.12.0

Jan 31st, 2023

What's Changed

• Added support for OAuth 2.0 PKCE by @MLukman in #386

New Contributors

• @MLukman made their first contribution in #386

Full Changelog: v2.11.0...v2.12.0