Sort imports, remove unused import

Author: rzhw

test/index.test.ts

@@ -15,9 +15,8 @@
  * limitations under the License.
  */
 
-import { promises as fs } from 'fs';
-import postcss from 'postcss';
 import plugin = require('../src');
+import postcss from 'postcss';
 import { toShortName } from '../src/minimal-renamer';
 
 async function run(input: string, options = {}): Promise<postcss.Result> {