simplify dfmt.copernicusmarine_credentials() function

[veenstrajelmer]

[CMCS-210] subset/get/open_dataset not saving credentials after prompting them (or maybe-login function like this one)

update on 25-3-2024: copernicusmarine>=1.0.7 has skip_if_user_logged_in argument for login() function, so dfmt.copernicusmarine_credentials() can be simplified

Also increase minimal version in pyproject.toml.

update 27-3:
new keyword works, but it does not check the correctness of the credentials:

import os
import copernicusmarine
os.environ["COPERNICUS_MARINE_SERVICE_USERNAME"] = "aa"
os.environ["COPERNICUS_MARINE_SERVICE_PASSWORD"] = "aa"
copernicusmarine.login(skip_if_user_logged_in=True)

Prints: "INFO - 2024-03-27T16:29:02Z - Credentials file stored in C:\Users\veenstra\.copernicusmarine\.copernicusmarine-credentials."

Also update: \site-packages\cachier\core.py:222: DeprecationWarning: ignore_cacheis deprecated and will be removed in a future release, usecachier__ alternative instead.

Update 9-4-2024: since last version 1.1.0 released last Friday, the Copernicus Marine credentials are checked again, so you can test the option --skip-if-user-logged-in in normal conditions now.