chore(dependabot): move rust toolchain to toml format

[ReenigneArcher]

Description

Move rust toolchain to toml format because current format is not supported by dependabot.

Screenshot

Issues Fixed or Closed

Type of Change

• 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 not work as expected)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated the docstring/documentation-blocks for new or existing methods/components