Fix: Schema: no index is created for primary()

[LaravelFreelancerNL]

Discussed in #52

^{Originally posted by LaravelFreelancerNL September 20, 2021}
No index is created for:
$collection->primary(['_to', '_from', 'mediable_type', 'tag']); It fails silently

Directly calling the index does work:
$collection->index(['_to', '_from', 'mediable_type', 'tag']);