Fix coverage extension load

Author: Jean85

composer.json

@@ -15,7 +15,8 @@
         "php-http/httplug": "^2.0",
         "php-http/message-factory": "^1.0",
         "php-http/message": "^1.6",
-        "symfony/options-resolver": "^2.6 || ^3.0 || ^4.0"
+        "symfony/options-resolver": "^2.6 || ^3.0 || ^4.0",
+        "leanphp/phpspec-code-coverage": "^4.2"
     },
     "require-dev": {
         "phpspec/phpspec": "^3.4 || ^4.2",

phpspec.ci.yml

@@ -4,7 +4,7 @@ suites:
         psr4_prefix: Http\Client\Common
 formatter.name: pretty
 extensions:
-    - PhpSpec\Extension\CodeCoverageExtension
+    LeanPHP\PhpSpec\CodeCoverage\CodeCoverageExtension: ~
 code_coverage:
     format: clover
     output: build/coverage.xml