Add typecheck-check into pull request template

[clairep94]

Fixes #issue-number - none

Adding this as I noticed it's not in the PR template yet and might be useful for folks wanting to contribute for the first time via typescript migration contributions

Changes:

I have verified that this pull request:

• has no linting errors (npm run lint)
• has no test errors (npm run test)
• is from a uniquely-named feature branch and is up to date with the develop branch.
• is descriptively named and links to an issue number, i.e. Fixes #123
• meets the standards outlined in the accessibility guidelines

[release-com]

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• p5.js-web-editor
  • app-tede787.release.editor.p5js.org/
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🔧Environment Status : https://app.release.com/public/Processing%20Foundation/env-f3000aa3ec

[raclim]

Thanks for adding this in!