⚠️ Security Release ⚠️

Fixes CVE CVE-2025-22150 GHSA-c76h-2ccp-4975 (embargoed until 22-01-2025).

What's Changed

• fix(#3736): back-port 183f8e9 to v6.x by @ggoodman in #3855
• fix(#3817): send servername for SNI on TLS (#3821) [backport] by @metcoder95 in #3864
• fix: sending formdata bodies with http2 (#3863) [backport] by @metcoder95 in #3866
• [Backport v6.x] fix: Fixed the issue that there is no running request when http2 goaway by @github-actions in #3877
• types: [backport] Update return type of RetryCallback (#3851) by @metcoder95 in #3876

Full Changelog: v6.21.0...v6.21.1