Update dependency undici-types to v6.21.0

[elastic-renovate-prod]

This PR contains the following updates:

Package	Type	Update	Change
undici-types (source)	dependencies	minor	6.20.0 -> 6.21.0

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Release Notes

nodejs/undici (undici-types)

v6.21.0

Compare Source

What's Changed

• [Backport v6.x] web: mark as uncloneable when possible (#​3709) by @​jazelly in https://github.com/nodejs/undici/pull/3744
• [Backport v6.x] fetch: fix content-encoding order by @​github-actions in https://github.com/nodejs/undici/pull/3764
• [Backport v6.x] fix: handle undefined deref() of WeakRef(socket) by @​github-actions in https://github.com/nodejs/undici/pull/3822
• [Backport v6.x] fix: range end is zero-indexed by @​github-actions in https://github.com/nodejs/undici/pull/3827

Full Changelog: nodejs/undici@v6.20.1...v6.21.0

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