Add Supabase to list of Hacktoberfest participants

[favuur]

• I have read and understand the Contributing.md requirements
• I do not intend to make low-value changes, just for swag. I am aware that my PR could otherwise be flagged as spam or invalid and may lead to permanent exclusion from the Hacktoberfest event.

Adding a new Hacktoberfest participant

• I did not edit the README.md file by hand
• I have checked to ensure the new participant is not a duplicate and has not already been added
• I am not adding a company from the blocklist
• I have added the participant according to the Contributing.md requirements

Updating an existing Hacktoberfest participant

• I did not edit the README.md file by hand
• I have updated the existing participant.yml file according to the Contributing.md requirements

Updating the README.md

• I have discussed and received approval from a maintainer (@benbarth, @SoftCreatR, or @crweiner)

[benbarth]

Hi @favuur, the participant file you've modified has no changes. Was this by mistake? I don't want to mark this PR as invalid if this was an honest mistake.