fix: parserPath type might be undefined on Eslint Flat Config

[krist7599555]

Fix this issue #584

to compatibility with Eslint Flat Config.
parserPath might be undefined and will throw error on worker. so check parserPath is string type before usage.

Maybe we can remove whole svelte block since eslint-plugin-svelte3 is deprecated

[changeset-bot]

🦋 Changeset detected

Latest commit: 092a6dd

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

This PR includes changesets to release 1 package

Name	Type
eslint-plugin-prettier	Patch

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[github-actions]

📊 Package size report   No changes

File	Before	After
Total (Includes all files)	24.7 kB	24.7 kB
Tarball size	8.2 kB	8.2 kB

Unchanged files

File	Size
eslint-plugin-prettier.d.ts	117 B
eslint-plugin-prettier.js	7.4 kB
LICENSE.md	1.1 kB
package.json	2.6 kB
README.md	7.9 kB
worker.js	5.6 kB

_{🤖 This report was automatically generated by pkg-size-action}

[JounQin]

@krist7599555 Thanks for raising PR to fix the issue, but CI is broken unexpectedly, can you fix it?

[krist7599555]

@JounQin might need a workflow approval