fix: Tests that failing on Windows

[pawelkg]

Description
See #7474

A lots of directory separator mismatch in path fixed.

CodeIgniter\Database\Migrations\MigrationRunnerTest::testMigrationUsesSameConnectionAsMigrationRunner
ErrorException: unlink(\writable\runner.sqlite): Resource temporarily unavailable
\tests\system\Database\Migrations\MigrationRunnerTest.php:477
Propably related to: https://bugs.php.net/bug.php?id=78930

CodeIgniter\HTTP\Files\FileMovingTest::testStore
ErrorException: mkdir(): No such file or directory

\system\HTTP\Files\UploadedFile.php:181
\system\HTTP\Files\UploadedFile.php:135
\system\HTTP\Files\UploadedFile.php:355
\tests\system\HTTP\Files\FileMovingTest.php:215

On Windows path was: WRITEPATH . 'uploads/vfs://path/to/file'

In addition change composer test command to work on slower computers.

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[kenjis]

Thank you for sending this PR.
But unfortunately It seems that no one is interested in this PR.
I cannot review because I don't use Windows.

Also, this PR contains multiple changes, so it is difficult to review.
I think it would be more likely to be reviewed if you sent multiple small PRs that address one issue each.

[kenjis]

To be honest, I don't like to write test code like this.
Because it is a bit more difficult to read.
So, I would like a different solution.

[maniaba]

@kenjis In my case, I usually prefer to use implode() for paths, which I find improves clarity and maintainability. Here's an example of how it could be refactored using implode()

$expected = implode(DIRECTORY_SEPARATOR, [APPPATH, 'Views', 'errors', 'html', 'error_404.php']);