Write a function called `validate_password` that takes a string as input and returns `True` if the input string is a valid password, and `False` otherwise. A valid password must satisfy the following criteria:
- At least 8 characters long
- Contains at least one uppercase letter
- Contains at least one lowercase letter
- Contains at least one digit
- Contains at least one special character from the set: !@#$%^&*
Use regular expressions (regex) to validate the password.
#### Example
Input: "Passw0rd!"
Output: True