fix jms/serializer versions (#15)

* fix jms/serializer versions
* add php 7.4 to travis
* fix travis badge

.travis.yml

@@ -3,6 +3,7 @@ language: php
 php:
     - 7.2
     - 7.3
+    - 7.4
 
 env:
     - JMS=0.12

README.md

@@ -1,9 +1,9 @@
-[![Build Status](https://img.shields.io/travis/retailcrm/atol-online-client/master.svg?style=flat-square)](https://travis-ci.org/retailcrm/atol-online-client)
+[![Build Status](https://app.travis-ci.com/retailcrm/atol-online-client.svg?branch=master)](https://app.travis-ci.com/retailcrm/atol-online-client)
 [![Latest stable](https://img.shields.io/packagist/v/retailcrm/atol-online-client.svg?style=flat-square)](https://packagist.org/packages/retailcrm/atol-online-client)
 
 # API-клиент для АТОЛ.Онлайн
 
-API-клиент на PHP для сервиса онлайн-фискализации платежей АТОЛ.Онлайн.
+API-клиент на PHP для сервиса онлайн-фискализации платежей АТОЛ.Онлайн
 
 ## Требования
 

composer.json

@@ -14,7 +14,7 @@
         "ext-curl": "*",
         "ext-json": "*",
         "guzzlehttp/guzzle": "~6.3",
-        "jms/serializer": "~0.12|~1.0|~2.0|~3.0",
+        "jms/serializer": "^0.12|^1.0|^2.0|^3.0",
         "symfony/validator": "~2.8|~3.0|~4.0",
         "doctrine/cache": "~1.6",
         "psr/log": "~1.0"