Fix bug with case sensitive CLA checks

This release fixes the bug that was noticed with the CLA check reporting wrongly due to case sensitivity.

CLA check and Don't merge label check

Fails the CI when a don't merge label gets added to a pull request.
Update the CLA check

Move CLA check to Github actions

In this release, we move the CLA check which was previously done using oppiabot(probot) to oppiabot(GitHub actions).

Update users responsibilities

This release features a change of responsibility for confirming an issue as a good first issue.
See #165 for more information.

Handle issue events

Prepare actions to handle issue labelled and assigned events.

Setup Release

This release handles the setup for the Github Actions