Remove string export from fixture values

test/fixtures/values.js

@@ -1,10 +1,8 @@
-const string = 'This is a test string';
-const buffer = Buffer.from(string);
+const buffer = Buffer.from('This is a test string');
 const base64 = buffer.toString('base64');
 const hexString = buffer.toString('hex');
 
 module.exports = {
-  string,
   buffer,
   base64,
   hexString