Consistent parens usage for arrow functions with body.

.internal/createCaseFirst.js

@@ -11,7 +11,7 @@ import toString from '../toString.js'
  * @returns {Function} Returns the new case function.
  */
 function createCaseFirst(methodName) {
-  return string => {
+  return (string) => {
     string = toString(string)
 
     const strSymbols = hasUnicode(string)