Automatically label bug report issues with bug tag

[ericwb]

This change automatically sets the label on an issue to bug if opened using the bug report template.

All Submissions:

• Have you followed the guidelines stated in CONTRIBUTING.md file?
• Have you checked to ensure there aren't any other open Pull Requests for the desired changed?

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

New Feature Submission:

• Does your submission pass the tests?
• Have you linted your code locally prior to submission?

Changes To Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them?

After these steps, you're ready to open a pull request.

a. Give a descriptive title to your PR.

b. Describe your changes.

c. Put `closes #XXXX` in your comment to auto-close the issue that your PR fixes (if such).

[Lendemor]

Good idea, thanks!