ci: removes non-required imports.

Author: matthewhartstonge

addon/components/paper-button.js

@@ -3,7 +3,6 @@
  */
 import Focusable from './-focusable';
 import { action } from '@ember/object';
-import { assert } from '@ember/debug';
 
 /**
  * @class PaperButton

addon/components/paper-radio.js

@@ -3,7 +3,6 @@
  */
 import PaperRadioBase from './paper-radio-base';
 import { action } from '@ember/object';
-import { assert } from '@ember/debug';
 
 /**
  * @class PaperRadio

addon/components/paper-tab.js

@@ -5,7 +5,6 @@ import Focusable from './-focusable';
 import { tracked } from '@glimmer/tracking';
 import { action } from '@ember/object';
 import { htmlSafe } from '@ember/template';
-import { assert } from '@ember/debug';
 
 /**
  * @class PaperTab