Add missing use statements for UnsupportedException

Author: jmikola

src/Operation/DropCollection.php

@@ -7,6 +7,7 @@
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Driver\Exception\RuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
+use MongoDB\Exception\UnsupportedException;
 
 /**
  * Operation for the drop command.

src/Operation/DropDatabase.php

@@ -6,6 +6,7 @@
 use MongoDB\Driver\Server;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Exception\InvalidArgumentException;
+use MongoDB\Exception\UnsupportedException;
 
 /**
  * Operation for the dropDatabase command.

src/Operation/DropIndexes.php

@@ -6,6 +6,7 @@
 use MongoDB\Driver\Server;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Exception\InvalidArgumentException;
+use MongoDB\Exception\UnsupportedException;
 
 /**
  * Operation for the dropIndexes command.