Enhanced rate limiting (#620)

[Damian89]

• Enhanced rate limiting

• Use time.Ticker correctly

Description

Please add a short description of pull request contents.
If this PR addresses an existing issue, please add the issue number below.

Fixes: #(issue number)

Additonally

• If this is the first time you are contributing to ffuf, add your name to CONTRIBUTORS.md.
  The file should be alphabetically ordered.
• Add a short description of the fix to CHANGELOG.md

Thanks for contributing to ffuf :)