nancy: Remove unnecessary logs when running without GITHUB_TOKEN env

[wiliansilvazup]

What happened:
When run Nancy tool in my local machine, in all projects golang show message:

WARN[0000] {HORUSEC_CLI} Nancy tool failed to query the GitHub API for updates.
This is most likely due to GitHub rate-limiting on unauthenticated requests.
To make authenticated requests please:
  1. Generate a token at https://github.com/settings/tokens
  2. Set the token by setting the GITHUB_TOKEN environment variable.
Instructions for generating a token can be found at:
https://help.github.com/articles/creating-a-personal-access-token-for-the-command-line.  

I believe it is a very repetitive message that can only be added to the documentation.

What you expected to happen:
I beleave this log is not necessary show in all analysis runned by horusec.

How to reproduce it (as minimally and precisely as possible):
Any project golang run GITHUB_TOKEN=""; horusec start -p .

Environment:

• Horusec version (use horusec version): v2.7.0-rc.1
• Operating System: linux