upgrade dependencies (php7)

Makefile

@@ -0,0 +1,4 @@
+.PHONY: tests
+
+tests:
+	phpunit

composer.json

@@ -15,8 +15,8 @@
     },
     "minimum-stability": "dev",
     "require": {
-        "php": ">=5.6.0",
+        "php": "^7.1.3",
-        "symfony/validator": "3.*",
+        "symfony/validator": "^4",
         "deblan/csv": "v2.0.*"
     }
 }

phpunit.xml

@@ -7,7 +7,6 @@
     convertWarningsToExceptions = "true"
     processIsolation            = "false"
     stopOnFailure               = "false"
-    syntaxCheck                 = "true"
     bootstrap                   = "vendor/autoload.php" >
 
 	<testsuites>

tests/ExampleTest.php

@@ -1,11 +1,13 @@
 <?php
 
+use PHPUnit\Framework\TestCase;
+
 /**
  * class ExampleTest.
  *
  * @author Simon Vieille <simon@deblan.fr>
  */
-class ExampleTest extends \PHPUnit_Framework_TestCase
+class ExampleTest extends TestCase
 {
     public function testExemple()
     {

tests/ValidatorTest.php

@@ -1,18 +1,19 @@
 <?php
 
+use PHPUnit\Framework\TestCase;
 use Deblan\Csv\CsvParser;
 use Deblan\CsvValidator\Validator;
 use Symfony\Component\Validator\Validation;
 use Symfony\Component\Validator\Constraints\NotBlank;
 use Symfony\Component\Validator\Constraints\Email;
 
-class ValidatorTest extends \PHPUnit_Framework_TestCase
+class ValidatorTest extends TestCase
 {
     public function testViolation()
     {
         $parser = $this->generateParser('example.csv');
         $validator = $this->generateValidator($parser);
-        $this->setExpectedException('\RuntimeException');
+        $this->expectException('\RuntimeException');
         $validator->isValid();
     }
 

tests/ViolationTest.php

@@ -1,9 +1,10 @@
 <?php
 
+use PHPUnit\Framework\TestCase;
 use Symfony\Component\Validator\ConstraintViolation;
 use Deblan\CsvValidator\Violation;
 
-class ViolationTest extends \PHPUnit_Framework_TestCase
+class ViolationTest extends TestCase
 {
     public function testViolation()
     {