fix: SqliteAdapter wrong week format fix #81

[RomainMazB]

The actual date format for the SQLiteAdapter is this one:

laravel-trend/src/Adapters/SqliteAdapter.php

Line 15 in 391849c

'week' => '%Y-%W',

But this causes an issue as it's a non ISO 8601 date format as stated in the SQLite documentation.

The correct format should be %G-%V but is only available after the version 3.46 which is relatively new:

• less than a year
• not the default version for Ubuntu 24.04
• not the laravel/sail installed version

In the case where the date format is not recognized (if you run under the ISO 8601 supported version), it returns null as stated in the documentation.

So I used the coalesce method to parse for both format to enforce backward compatibility.