fix(importer): added %Y.%m.%d. + tests for guess_date_format

[vmatt]

Description:

This pull request introduces a minor update to the DATE_FORMATS array in the frappe/utils/data.py by adding a new date format "%Y.%m.%d." to cater to the specific needs observed in Hungarian date formatting, where dates end with a period (e.g., 2024.04.04.).

Additionally, I have expanded the unit testing for the guess_date_format. This is reflected in changes to the frappe/tests/test_utils.py.

Key Changes:

• Date Format Addition: Included a new date format "%Y.%m.%d." in the DATE_FORMATS array to support the Hungarian date format.
• Unit Tests: Added test case in TestDateUtils class to verify the guessing logic handles a broad set of date and time formats correctly.

Caveats & Future Directions:

• The current implementation of guess_date_format might still encounter ambiguities with certain date formats (e.g., 23-04-24 can be parsed in multiple ways). A proposed future enhancement is to allow users to specify the date format explicitly during data import, thus minimizing errors and improving data integrity.

How to test:
Ensure you have set up your development environment correctly and follow these steps:

1. Checkout this branch.
2. Run the updated unit tests using bench --site [your-site-name] run-tests --module frappe.tests.test_utils.TestDateUtils.
3. Review the test output and verify that all new tests pass without errors.

Orginal pull req: #25940
Your feedback is welcomed!

[vmatt]

hey @ankush, can you please trigger a tett run for the unit tests?

[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed within 3 days if no further activity occurs, but it only takes a comment to keep a contribution alive :) Also, even if it is closed, you can always reopen the PR when you're ready. Thank you for contributing.

[vmatt]

@ankush ?