Write test file directly because grunt keeps getting EEXIST errors fr…

…om mkdir.

test/unit-tests.js

@@ -1,3 +1,4 @@
+const fs = require('fs');
 const grunt = require('grunt');
 const jsonlint = require('@prantlf/jsonlint');
 const validator = require('@prantlf/jsonlint/lib/validator');
@@ -265,7 +266,7 @@ function testReformattingFile(indent) {
   }
 
   // Build an unformatted file for testing.
-  grunt.file.write(`${__dirname}/reformat-this.json`, '{"somethingsomething":"something","something":"dark side"}');
+  fs.writeFileSync(`${__dirname}/reformat-this.json`, '{"somethingsomething":"something","something":"dark side"}', { encoding: 'utf8' });
 
   runWithFiles(grunt, jsonlint, [ 'test/reformat-this.json' ], options);