Fix behat coverage not generated (#43)

Author: yoanm

composer.json

@@ -37,7 +37,7 @@
  },
  "require-dev": {
  "ext-json": "*",
- "behat/behat": "^3.9.0",
+ "behat/behat": "^3.9.0,<=3.16.1",
  "dvdoug/behat-code-coverage": "^5.0",
  "phpspec/prophecy": "^1.15",
  "phpspec/prophecy-phpunit": "^2.0",