Update cargo in base taskcluster dockerfile to 1.85

[oskirby]

Description

It seems that dependabot is having troubles updating the Cargo.lock file due to a version incompatibility with the cargo version on the taskcluster Docker containers. The problem occurs because the base build image uses Cargo 1.75. So lets update that to 1.85.

There is an argument to be made that we should go even newer (eg: to match #11275)

Reference

Example dependabot failure: #11320

Checklist

• My code follows the style guidelines for this project
• I have not added any packages that contain high risk or unknown licenses (GPL, LGPL, MPL, etc. consult with DevOps if in question)
• I have performed a self review of my own code
• I have commented my code PARTICULARLY in hard to understand areas
• I have added thorough tests where needed

[jcristau]

Would it be worth looking at bumping the base image from 22.04 to something newer, or would that affect the build's installability on older distros?

[oskirby]

There shouldn't be anything preventing us from updating the base image to something newer. I can give that a try while we're at it.