Removed Gradflow due to the site no longer being functional

[devzenq]

Their job board has been down for over 2 months

Thinking about making a pull request?

You don't need to! Just make an issue asking to be added as a contributor, and we'll add you!

Please only make pull requests if:

• you're changing the overall structure
• you're changing the design of the entire website
• you want points for Hacktoberfest, or something like that

Thank you!

[yutotakano]

Thanks for the contribution!

You should've received an invitation as a contributor now, please merge this PR on your own as a confirmation! :)