avoid allocations by using mirror functions

[alexandear]

By submitting this pull request, I confirm that my contribution is made under the terms of the MIT license.

Problem/Feature

The PR refactors code to use regexp.MatchString to avoid one allocation when converting byte slice to string.

Description of Changes:

• Replace regexp.Match(s, []byte(input)) with regexp.MatchString(s, input) where input is string.

Checklist

• I have self-reviewed the changes being requested
• I have updated the documentation (check issue ticket 📋Update documentation if the PR introduces a new feature!📋 #218)

Additional info

This was found with the help of mirror linter, which can be enabled in golangci-lint config.

[Ujstor]

LGTM