fix(xo-lib): handle URLs ending with /

Thanks @rushikeshjadhav

packages/xo-lib/src/index.js

@@ -1,4 +1,5 @@
 import JsonRpcWebSocketClient, { OPEN, CLOSED } from 'jsonrpc-websocket-client'
+import trimEnd from 'lodash/trimEnd'
 import { BaseError } from 'make-error'
 
 // ===================================================================
@@ -14,7 +15,7 @@ export class XoError extends BaseError {}
 export default class Xo extends JsonRpcWebSocketClient {
   constructor(opts) {
     const url = opts != null ? opts.url : '.'
-    super(`${url === '/' ? '' : url}/api/`)
+    super(`${trimEnd(url, '/')}/api/`)
 
     this._credentials = opts != null ? opts.credentials : null
     this._user = null