Remove unused dependency on doctrine/common

Author: Bocmah

composer.json

@@ -12,8 +12,7 @@
         }
     ],
     "require": {
-        "php": ">=7.0",
-        "doctrine/common": "^2.8"
+        "php": ">=7.0"
     },
     "require-dev": {
         "phpunit/phpunit": "^6.4",

tests/SpecificationTest.php

@@ -2,12 +2,6 @@
 
 namespace Tanigami\Specification;
 
-use Doctrine\Common\Collections\Criteria;
-use Doctrine\Common\Collections\Expr\ClosureExpressionVisitor;
-use Doctrine\Common\Collections\Expr\Comparison;
-use Doctrine\Common\Collections\Expr\CompositeExpression;
-use Doctrine\Common\Collections\Expr\ExpressionVisitor;
-use Doctrine\Common\Collections\Expr\Value;
 use PHPUnit\Framework\TestCase;
 use stdClass;