Update main.lua

[enekolizarraga]

optimized CPU consumption

Describe Pull request
I have optimized the CPU Consumption of the script while is the player is not using a weapon.

If your PR is to fix an issue mention that issue here

Questions (please complete the following information):

• Have you personally loaded this code into an updated qbcore project and checked all it's functionality? Yes
• Does your code fit the style guidelines? yes
• Does your PR fit the contribution guidelines? yes