Change new contributor workflow settings for Rust

[TommyCpp]

Similar to #1023 , we'd like to change the setting of approving workflow runs from public forks to

Require approval for first-time contributors who are new to GitHub

to help new contributors.

Since we don't have access, can someone from TC help out? Thanks
cc @open-telemetry/rust-approvers

[arminru]

Hey @TommyCpp! I changed the setting as requested so we can give it a try.
Please keep an eye on it and let us know if you see any suspicious activity. Thank you.