Promote some Zipline Contributors to Committers

[caiocamatta-stripe]

Proposal: Add Piyush, Nikhil, and Varant from Zipline AI to the Contributors list.

Motivation: Nikhil and Varant are two of Chronon's initial creators. Piyush has worked with Chronon for over two years, making significant contributions. All three are actively helping to increase adoption of the project and continue to make important contributions.

Process: In accordance with the guidelines in the GOVERNANCE.md document, this proposal requires consensus and at least 3 votes from active PMC members. Voting will be open for 3 days.

I will share this Issue directly with all active PMC members for visibility.

[mears-stripe]

+1, I'm supportive.

[hzding621]

+1!

[pengyu-hou]

Plus one to this. And we are thrilled to welcome back our old friends.

As Airbnb is still using the public repo for internal usage, if we encounter any breaking changes, please bear with us to fix it forward. Thanks for the understanding.

[pkundurthy]

+1!

[nikhilsimha]

we are honored to be working with you all (again)!

[piyush-zlai]

Thanks folks! Excited to keep pushing the project forward!