fix: content not returned anymore by add

The change all-contributors#356 seem to break the formatting of the file .all-contributorsrc. Instead of formatting the content, it formats "undefined".

See:
- all-contributors#356 (comment)
- all-contributors#356 (comment)

src/util/__tests__/formatting.js

@@ -23,13 +23,13 @@ const presentConfigFileExpected = `{
 `
 
 test('falls back to JSON.stringify when the configPath cannot resolve to a config', () => {
-  expect(formatting.formatConfig(absentFile, content)).toBe(
+  expect(formatting.formatConfig(content, absentFile)).toBe(
     absentConfigFileExpected,
   )
 })
 
 test('uses Prettier when the configPath can resolve to a config', () => {
-  expect(formatting.formatConfig(presentFile, content)).toBe(
+  expect(formatting.formatConfig(content, presentFile)).toBe(
     presentConfigFileExpected,
   )
 })

src/util/formatting.js

@@ -1,4 +1,4 @@
-function formatConfig(configPath, content) {
+function formatConfig(content, configPath) {
   const stringified = JSON.stringify(content, null, 2)
   try {
     const prettier = require('prettier')