Create FUNDING.yml

[ParadoxV5]

• The Jira issue number for this PR is: MDEV-______

Description

Configure a Sponsor button to surface a link to mariadb.org/donate

https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/displaying-a-sponsor-button-in-your-repository

Note that to take effect, an admin needs to enable the button in https://github.com/MariaDB/server/settings.

(As a Corporation employee, I clarify that I’m aware that Foundation memebers like the Corporation fund the Foundation and not the other way around.)

Release Notes

N/A

How can this PR be tested?

N/A
Check that the GitHub home page has a “❤️ Sponsor” button that links to https://mariadb.org/donate/

Basing the PR against the correct MariaDB version

• This is a new feature or a refactoring, and the PR is based against the main branch.
• This is a bug fix, and the PR is based against the earliest maintained branch in which the bug can be reproduced.

PR quality check

• I checked the CODING_STANDARDS.md file and my PR conforms to this where appropriate.
• For any trivial modifications to the PR, I am ok with the reviewer making the changes themselves.