Fix deprecation warning regarding implicit injections

[mayatron]

The following deprecation warning appears on application launch, starting with Ember 3.26.0:

DEPRECATION: A value was injected implicitly on the 'emberSpinnerPrefixConfig' property of an instance of <monolith@component:ember-spinner::ember195>. Implicit injection is now deprecated, please add an explicit injection for this value. If the injected value is a service, consider using the @service decorator. [deprecation id: implicit-injections] See https://deprecations.emberjs.com/v3.x#toc_implicit-injections for more details.

This appears to be caused by:

ember-cli-spinjs/app/initializers/ember-spinner.js

Lines 7 to 15 in 667b1f1

	export default {
	name: 'ember-spinner-prefix',
	initialize: function() {
	let application = arguments[1] || arguments[0];
	application.register('ember-spinner:main', emberSpinnerPrefix, {instantiate: false});
	application.inject('component:ember-spinner', 'emberSpinnerPrefixConfig', 'ember-spinner:main');
	}
	};