fix(deps): update dependency yjs to ^13.6.21 (stable29)

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
yjs (source)	^13.6.20 -> ^13.6.21

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Release Notes

yjs/yjs (yjs)

v13.6.21

Compare Source

• fix #​657 - relative positions issue when using followUndoneDeletions=false f583d2a
• lint 1b0f2e5
• add nodejs specific tests 4404d09
• Merge pull request #​679 from hoangqwe159/main d4d4ae5
• Add PSPDFKit binding to README.md 4ffd370
• Merge pull request #​676 from himself65/patch-1 0419b74
• add Open Collaboration Tools as a user c951f2b
• docs: remove @toeverything/y-indexeddb 4e2d3c8
• update readme 8dc1296
• add stars to providers that sponsor yjs 4329997
• Merge pull request #​671 from carlossantos74/main 2b7ea8a
• add SuperViz Provider in yjs README 4f47355
• [funding.json] fix some validation issues 6074f80
• fix errors in funding.json 42bbb44
• add funding.json cc2d732
• add y-crdt elexir bindings e804dd7

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