Fix doctrine migrations

Context:

The commit 060d162 updated the composer
dependencies and introduced some breakages.

The composer.lock was using the doctrine/doctrine-migrations-bundle:v1.3.2
and the doctrine/migrations:v1.8.1 versions.

The doctrine/migrations package major upgrade to the v2.0.0 version changed
the autoload namespace of AbstractMigration class and started to use the new
PHP 7.0 return type declarations feature.

Fix #317

src/Migrations/Version20170912085504.php

@@ -4,7 +4,7 @@
 
 namespace DoctrineMigrations;
 
-use Doctrine\DBAL\Migrations\AbstractMigration;
+use Doctrine\Migrations\AbstractMigration;
 use Doctrine\DBAL\Schema\Schema;
 
 /**
@@ -15,7 +15,7 @@ class Version20170912085504 extends AbstractMigration
     /**
      * @param Schema $schema
      */
-    public function up(Schema $schema)
+    public function up(Schema $schema) : void
     {
         // this up() migration is auto-generated, please modify it to your needs
         $this->abortIf($this->connection->getDatabasePlatform()->getName() !== 'mysql', 'Migration can only be executed safely on \'mysql\'.');
@@ -188,7 +188,7 @@ public function up(Schema $schema)
     /**
      * @param Schema $schema
      */
-    public function down(Schema $schema)
+    public function down(Schema $schema) : void
     {
         // this down() migration is auto-generated, please modify it to your needs
         $this->abortIf($this->connection->getDatabasePlatform()->getName() !== 'mysql', 'Migration can only be executed safely on \'mysql\'.');

src/Migrations/Version20170913125128.php

@@ -4,7 +4,7 @@
 
 namespace DoctrineMigrations;
 
-use Doctrine\DBAL\Migrations\AbstractMigration;
+use Doctrine\Migrations\AbstractMigration;
 use Doctrine\DBAL\Schema\Schema;
 
 /**
@@ -15,7 +15,7 @@ class Version20170913125128 extends AbstractMigration
     /**
      * @param Schema $schema
      */
-    public function up(Schema $schema)
+    public function up(Schema $schema) : void
     {
         // this up() migration is auto-generated, please modify it to your needs
         $this->abortIf($this->connection->getDatabasePlatform()->getName() !== 'mysql', 'Migration can only be executed safely on \'mysql\'.');
@@ -47,7 +47,7 @@ public function up(Schema $schema)
     /**
      * @param Schema $schema
      */
-    public function down(Schema $schema)
+    public function down(Schema $schema) : void
     {
         // this down() migration is auto-generated, please modify it to your needs
         $this->abortIf($this->connection->getDatabasePlatform()->getName() !== 'mysql', 'Migration can only be executed safely on \'mysql\'.');

src/Migrations/Version20171003103916.php

@@ -4,7 +4,7 @@
 
 namespace DoctrineMigrations;
 
-use Doctrine\DBAL\Migrations\AbstractMigration;
+use Doctrine\Migrations\AbstractMigration;
 use Doctrine\DBAL\Schema\Schema;
 use Sylius\Component\Attribute\AttributeType\SelectAttributeType;
 use Sylius\Component\Product\Model\ProductAttributeInterface;
@@ -32,7 +32,7 @@ public function setContainer(?ContainerInterface $container = null): void
     /**
      * @param Schema $schema
      */
-    public function up(Schema $schema): void
+    public function up(Schema $schema) : void
     {
         // this up() migration is auto-generated, please modify it to your needs
         $this->abortIf($this->connection->getDatabasePlatform()->getName() != 'mysql', 'Migration can only be executed safely on \'mysql\'.');
@@ -68,7 +68,7 @@ public function up(Schema $schema): void
     /**
      * @param Schema $schema
      */
-    public function down(Schema $schema): void
+    public function down(Schema $schema) : void
     {
         // this down() migration is auto-generated, please modify it to your needs
         $this->abortIf($this->connection->getDatabasePlatform()->getName() != 'mysql', 'Migration can only be executed safely on \'mysql\'.');

src/Migrations/Version20180102140039.php

@@ -4,23 +4,23 @@
 
 namespace DoctrineMigrations;
 
-use Doctrine\DBAL\Migrations\AbstractMigration;
+use Doctrine\Migrations\AbstractMigration;
 use Doctrine\DBAL\Schema\Schema;
 
 /**
  * Auto-generated Migration: Please modify to your needs!
  */
 class Version20180102140039 extends AbstractMigration
 {
-    public function up(Schema $schema)
+    public function up(Schema $schema) : void
     {
         // this up() migration is auto-generated, please modify it to your needs
         $this->abortIf($this->connection->getDatabasePlatform()->getName() !== 'mysql', 'Migration can only be executed safely on \'mysql\'.');
 
         $this->addSql('CREATE INDEX IDX_16C8119EE551C011 ON sylius_channel (hostname)');
     }
 
-    public function down(Schema $schema)
+    public function down(Schema $schema) : void
     {
         // this down() migration is auto-generated, please modify it to your needs
         $this->abortIf($this->connection->getDatabasePlatform()->getName() !== 'mysql', 'Migration can only be executed safely on \'mysql\'.');