fix: reset dependency read versions after reaction execution

[trueadm]

Before submitting the PR, please make sure you do the following

• It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs
• Prefix your PR title with feat:, fix:, chore:, or docs:.
• This message body should clearly illustrate what problems it solves.
• Ideally, include a test that fails without this PR but passes with it.
• If this PR changes code within packages/svelte/src, add a changeset (npx changeset).

Tests and linting

• Run the tests with pnpm test and lint the project with pnpm lint

[changeset-bot]

🦋 Changeset detected

Latest commit: b428f01

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

This PR includes changesets to release 1 package

Name	Type
svelte	Patch

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[Rich-Harris]

preview: https://svelte-dev-git-preview-svelte-14964-svelte.vercel.app/

this is an automated message

[github-actions]

Playground

pnpm add https://pkg.pr.new/svelte@14964

[paoloricciuti]

Still not the complete fix: it only works the first time

REPL

[trueadm]

Still not the complete fix: it only works the first time

REPL

Put up a better fix

[paoloricciuti]

We just beat the record for most collaborators on the minimal change

1 fix from @trueadm
1 comment from @dummdidumm
1 test from @paoloricciuti
1 changeset from @Rich-Harris

lol