perf(misconf): do not convert contents of a YAML file to string

[nikpivkin]

Description

To work with bytes, it is better to use the bytes package instead of converting bytes to a string.

Checklist

• I've read the guidelines for contributing to this repository.
• I've followed the conventions in the PR title.
• I've added tests that prove my fix is effective or that my feature works.
• I've updated the documentation with the relevant information (if needed).
• I've added usage information (if the PR introduces new options)
• I've included a "before" and "after" example to the description (if the PR is a user interface change).

[simar7]

nice! did you measure how much better this performs? We could add that info to the release notes.