Fix bug where username validation function returns True even when it starts with a non-ascii character

[Mys7erio]

Expected Behavior

Should return False if the username starts with a non-ascii character

Actual Behavior

Returns True even if the username starts with a non-ascii character such as a period (.)

Steps to Reproduce the Problem

1. Add the following line at the end of the script: print(validate_user(".blue.kale", 3))
2. Run the script using python3 [script_name].py
3. Output: True

Specifications

• Version: Python 3.9.2
• Platform: Linux linux-instance 5.10.0-26-cloud-amd64 #1 SMP Debian 5.10.197-1 (2023-09-29) x86_64 GNU/Linux