chore(radio): fix typo in test name (#14000)

Author: lx1036

src/lib/radio/radio.spec.ts

@@ -217,7 +217,7 @@ describe('MatRadio', () => {
       expect(radioInstances[1].checked).toBe(true);
     });
 
-    it('should deselect all of the checkboxes when the group value is cleared', () => {
+    it('should deselect all of the radios when the group value is cleared', () => {
       radioInstances[0].checked = true;
 
       expect(groupInstance.value).toBeTruthy();