Fixed empty ssh password case.

[adrianlasota]

fix: Changed if statements for ssh password to allow empty string

This pull request makes small but important improvements to the handling of None values in conditional checks for SSH password authentication in the sshtunnel.py file. These changes ensure more explicit comparisons, improving code clarity and reducing potential errors.

• Improved conditional checks for None:
  • In _consolidate_auth, updated the condition to explicitly check if ssh_password is None rather than relying on its falsy evaluation. This ensures clarity when distinguishing between None and other falsy values like an empty string.
  • In _connect_to_gateway, replaced the implicit truthiness check of self.ssh_password with an explicit comparison to None, making the intent clearer and avoiding ambiguity.