Move requests (required for SSR only) to an extra

[akx]

Since only SSR support requires requests, it shouldn't be installed (along with its transitive dependencies) for projects that don't require SSR.

[BrandonShar]

I'm somewhat torn on this one because I really value ease of setup, but I would guess that SSR is a significant minority of new installs; I've personally never used it.

I'm strongly leaning towards merging this, but I'd be interested in some more opinions before I do.

@svengt what do you think?

[svengt]

@BrandonShar @akx I agree this dependency could be marked as optional. However, I'm hesitant about making this change now since it would be breaking - anyone currently relying on inertia-django to handle the requests dependency would need to either install it themselves or add the extra flag to their requirements.

My suggestion would be to leave this as is until we're planning other breaking changes, so we can bundle them together in a proper major version update.