Fix password validator uppercase validation

[delaewoenamavemee-crypto]

Description

Fixes the password validator so that a password must contain at least one uppercase letter.

Problem

The password validator was checking for any letter instead of specifically checking for an uppercase letter. This allowed passwords without uppercase characters to be accepted as valid.

Changes Made

• Updated the password validation check to require an uppercase letter.
• Added a test to verify that a password without an uppercase letter is rejected.

Testing

The test was run successfully using:

python -m unittest test_password_validator.py

Result: OK

[github-actions]

Hi @delaewoenamavemee-crypto! 👋

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