fix: escape < in attribute strings

[dummdidumm]

Svelte 4 version of #11411

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[changeset-bot]

🦋 Changeset detected

Latest commit: fb22bd9

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

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[Pierrci]

Is there any chance this could be backported to Svelte 3, too? 😅

[Uzume]

It seems like this issue was introduced in #5701. This is a great example of both performance sensitive and security sensitive code.

It seems like #8434 is no longer needed as this PR (re)introduces < always being HTML entity escaped in attributes.