[rust] Format Selenium Manager Rust logic using cargo fmt

[bonigarcia]

Description

This PR makes formatting change on the Rust logic (Selenium Manager) using cargo fmt, as suggested in #11213.

Motivation and Context

Development of Selenium Manager M2.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have read the contributing document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[diemol]

Thank you, @bonigarcia!