Update cargo-c to 0.7.2
Summary:
Changelog:
- Use cargo 0.50.
- Pin the serde version to be compatible.
Test Plan: Rebuilt rav1e with this version.
Reviewers: Triage Team, JoshStrobl
Reviewed By: Triage Team, JoshStrobl
Subscribers: JoshStrobl
Differential Revision: https://dev.getsol.us/D10455