Implement a GitHub workflow to welcome first-time contributors

[binadamu-isiyoonekana]

Aim

Implement a new GitHub Actions workflow to thank first-time contributors when they submit their seminal pull request (PR) to the project.
The intention of this welcome workflow is to present various point of friction contributors can use to be welcomed to the project's ecosystem's community (once a contribution, always a contribution :)).

Assumptions

• None

Acceptance criteria

• The first-interaction workflow is used to implement this welcoming message
• This welcome workflow is executed only once, when the contributor submits her/his first PR
• The welcome message presents the major communication channels the contributor can use to communicate with the project's community.

Risks

• None

Dependencies

• None

References

• first-interaction: GitHub Actions workflow used to welcome first-time contributors, inviting them to subscribe to various community channels (e.g. Telegram, ...)