PHPLIB-1650: Fix Int64 detection in Matches::isNumeric()

This was discovered by adding flexible numeric comparisons to the $$lte tests.

Author: jmikola

tests/UnifiedSpecTests/Constraint/Matches.php

@@ -4,6 +4,7 @@
 
 use LogicException;
 use MongoDB\BSON\Document;
+use MongoDB\BSON\Int64;
 use MongoDB\BSON\Serializable;
 use MongoDB\BSON\Type;
 use MongoDB\Model\BSONArray;