fix: singleton plugins tests

Author: atomiks

test/TippySingleton.test.js

@@ -298,7 +298,7 @@ describe('<TippySingleton />', () => {
       </TippySingleton>,
     );
 
-    expect(instance.plugins).toEqual(plugins);
+    expect(instance.plugins.slice(1)).toEqual(plugins);
   });
 });
 

test/useSingleton.test.js

@@ -263,7 +263,7 @@ describe('The useSingleton hook', () => {
       const singleton = useSingleton({
         plugins,
         onCreate(instance) {
-          expect(instance.plugins).toEqual(plugins);
+          expect(instance.plugins.slice(1)).toEqual(plugins);
         },
       });