Fix escaping of column name for specific alter table case

When changing the length of a field, the column name needs to be escaped
properly.

lib/Doctrine/DBAL/Platforms/PostgreSqlPlatform.php

@@ -510,7 +510,7 @@ class PostgreSqlPlatform extends AbstractPlatform
             }
 
             if ($columnDiff->hasChanged('length')) {
-                $query = 'ALTER ' . $column->getName() . ' TYPE ' . $column->getType()->getSqlDeclaration($column->toArray(), $this);
+                $query = 'ALTER ' . $oldColumnName . ' TYPE ' . $column->getType()->getSqlDeclaration($column->toArray(), $this);
                 $sql[] = 'ALTER TABLE ' . $diff->getName()->getQuotedName($this) . ' ' . $query;
             }
         }