breaking: remove "netrc" authentication type (#640)

BREAKING CHANGE: Authentication with `"netrc"` is no longer supported:

```js
github.authenticate({
  type: "netrc"
})
```

Instead, use the [netrc](https://www.npmjs.com/package/netrc) package directly and pass username/password to `"basic"` authentication

```js
const netrc = require('netrc')
const myNetrc = netrc()

github.authenticate({
  type: 'basic',
  username: myNetrc['api.github.com'].login,
  password: myNetrc['api.github.com'].password
})
```

Author: copperwall

README.md

@@ -128,11 +128,6 @@ github.authenticate({
   type: 'integration',
   token: 'jwt'
 })
-
-// ~/.netrc
-github.authenticate({
-  type: 'netrc'
-})
 ```
 
 Note: `authenticate` is synchronous because it only stores the

lib/index.js

@@ -4,7 +4,6 @@ var fs = require('fs')
 
 var HttpsProxyAgent = require('https-proxy-agent')
 var mime = require('mime')
-var netrc = require('netrc')
 var toCamelCase = require('lodash/camelCase')
 
 var error = require('./error')
@@ -349,8 +348,8 @@ var Client = module.exports = function (config) {
       this.auth = false
       return
     }
-    if (!options.type || 'basic|oauth|client|token|integration|netrc'.indexOf(options.type) === -1) {
-      throw new Error("Invalid authentication type, must be 'basic', 'integration', 'oauth', 'client' or 'netrc'")
+    if (!options.type || 'basic|oauth|client|token|integration'.indexOf(options.type) === -1) {
+      throw new Error("Invalid authentication type, must be 'basic', 'integration', 'oauth', or 'client'")
     }
     if (options.type === 'basic' && (!options.username || !options.password)) {
       throw new Error('Basic authentication requires both a username and password to be set')
@@ -720,14 +719,6 @@ var Client = module.exports = function (config) {
           basic = Buffer.from(this.auth.username + ':' + this.auth.password, 'ascii').toString('base64')
           headers['Authorization'] = 'Basic ' + basic
           break
-        case 'netrc':
-          var auth = netrc()[host]
-          if (!auth) {
-            throw new Error("~/.netrc authentication type chosen but no credentials found for '" + host + "'")
-          }
-          basic = Buffer.from(auth.login + ':' + auth.password, 'ascii').toString('base64')
-          headers['Authorization'] = 'Basic ' + basic
-          break
         default:
           break
       }

package.json

@@ -30,8 +30,7 @@
     "follow-redirects": "1.2.6",
     "https-proxy-agent": "^2.1.0",
     "lodash": "^4.17.4",
-    "mime": "^2.0.3",
-    "netrc": "^0.1.4"
+    "mime": "^2.0.3"
   },
   "devDependencies": {
     "@octokit/fixtures": "^5.4.0",