Fixes diagnostics. Closes #215

[garrytrinder]

• Increment version to 0.23.3
• Fixes diagnostics. Closes [BUG]: Diagnostics remain if a file is deleted #215

[Copilot]

Pull Request Overview

This PR addresses issue #215 by fixing the diagnostics behavior when files are deleted, along with a version bump to 0.23.3.

• Adds a listener for file deletion events in src/documents.ts to remove corresponding entries from the collection.
• Updates the version in package.json.
• Reflects these changes in CHANGELOG.md.

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/documents.ts	Added a subscription to handle file deletion and update diagnostics.
package.json	Updated the version to 0.23.3.
CHANGELOG.md	Updated changelog to document the diagnostics fix and version bump.