Reset modal after adding event

[romanstetsyk]

Description

Reset the form after adding an event by clicking the 'close' button or clicking on the modal backdrop.

Type of change

Please select everything applicable. Please, do not delete any lines.

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update
• [ ] This change requires an update to testing

Issue

• [x] Is this related to a specific issue? If so, please specify: #425

Checklist:

• [x] This PR is up to date with the main branch, and merge conflicts have been resolved
• [x] I have executed npm run test and all tests have passed successfully or I have included details within my PR on the failure.
• [x] I have executed npm run lint and resolved any outstanding errors. Most issues can be solved by executing npm run format
• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] My changes generate no new warnings