Resolve this-property-fallback deprecation

[rmachielse]

This resolves two deprecations related to https://deprecations.emberjs.com/v3.x#toc_this-property-fallback:

DEPRECATION: The direction property path was used in a template for the ember-sortable/templates/components/sortable-group.hbs component without using this. This fallback behavior has been deprecated, all properties must be looked up on this when used in the template: {{this.direction}} [deprecation id: this-property-fallback] See https://deprecations.emberjs.com/v3.x#toc_this-property-fallback for more details.

DEPRECATION: The model property path was used in a template for the ember-sortable/templates/components/sortable-group.hbs component without using this. This fallback behavior has been deprecated, all properties must be looked up on this when used in the template: {{this.model}} [deprecation id: this-property-fallback] See https://deprecations.emberjs.com/v3.x#toc_this-property-fallback for more details.

[rmachielse]

@alexlafroscia @ygongdev this simple change removes a lot of deprecation warnings from our app and seems compatible with all supported versions. Any chance on a quick merge & release?

[rmachielse]

@alexlafroscia @ygongdev anyone able to have a look at this?

[alexlafroscia]

Sorry for the delay; there's been a lot going on in my personal life and I'm just coming back to OSS now!

[rmachielse]

No worries at all, appreciate the effort on this and other work! @alexlafroscia