Password Strength Checker

This is a simple Go program that checks the strength of a given password using regular expressions.

The program defines a checkPasswordStrength function which takes in a string (password) as input. The function uses regular expressions to check for the presence of different types of characters in the password and assigns a strength value based on the presence of those characters.

The function checks for the presence of uppercase letters, lowercase letters, digits and special characters. If a password contains all of these types of characters, the password is considered strong. If a password contains at least three types of characters, the password is considered medium, otherwise, the password is considered weak.