Fixing Namespace Option Ending with Backslash in LiftMigration Command

[BadJacky]

This PR addresses an issue in the LiftMigration command where the namespace option could end with a backslash (\\). In the original code, if the namespace option ended with a backslash, it would result in two consecutive backslashes when concatenating the model name. This could lead to unexpected issues.

In this PR, I've used the rtrim function to ensure that the namespace option does not end with a backslash before concatenating the model name.

Here's the modified line of code:

$class = rtrim($this->option('namespace'), '\\') . '\\' . $this->argument('model'); // @phpstan-ignore-line

This change has passed all tests, including a new test case specifically designed to check if a migration file is correctly generated when the namespace option ends with two backslashes (\\).

Please review this PR and feel free to provide any feedback or suggestions.

[WendellAdriel]

Thanks for the contribution!!! 🔥 💪