chore: Add issue and PR templates

[klkucaj]

What does this PR do?

This PR adds templates to streamline the contribution process by providing:

• Issue Templates: Predefined structures for bug reports, feature requests, and improvement suggestions.
• Pull Request Template: A standardized format for PR submissions, ensuring consistency and clarity.

Why is this important?

Having these templates in place helps:

• Ensure contributors provide necessary details for issues and PRs.
• Improve the overall quality and maintainability of the repository.
• Make the review process faster and more efficient.

Changes Included

1. Added the following issue templates in .github/ISSUE_TEMPLATE/:
   • bug_report.yml for reporting bugs.
   • feature_request.yml for suggesting new features.
   • improvement.yml for proposing improvements.
2. Added a pull request template in .github/pull_request_template.md.

Related Issue

• Closes Add issue and PR template #21

Additional Notes

• This PR focuses solely on adding templates and does not include any code changes.
• Contributors are encouraged to follow these templates for better collaboration.