add loader test snapshot

src/components/__tests__/loader.test.js

@@ -0,0 +1,11 @@
+import React from "react"
+import renderer from "react-test-renderer"
+
+import Loader from "../loader"
+
+describe("Loader", () => {
+  it("renders correctly", () => {
+    const tree = renderer.create(<Loader />).toJSON()
+    expect(tree).toMatchSnapshot()
+  })
+})