Fix secure in password

app/models/user.rb

@@ -17,7 +17,8 @@ class User < ApplicationRecord
   validates :email, presence: true, format: { with: VALID_EMAIL_REGEX },
     uniqueness: { case_sensitive: false }
 
-  validates :password, allow_nil: true, length: { minimum: 6, too_short: "is blank or too short" }
+  PASSWORD_FORMAT = /\A(?=.{8,})(?=.*\d)(?=.*[a-z])(?=.*[A-Z])/x
+  validates :password, allow_nil: true, format: { with: PASSWORD_FORMAT, message: "is too short or not strength" }
 
   def self.new_remember_token
     SecureRandom.urlsafe_base64