Clockwork breaks unit tests running on SQLite3

[jedateach]

Looks like the DB proxy is breaking somewhere. Might be worth getting this module onto TravisCI to test all databases easily/regularly. It'll also help pick up issues if/when SS db core stuff changes.

1) ShoppingCartControllerTest::testRemoveFromCart
Couldn't run query: TRUNCATE "SQLiteEnums" | near "TRUNCATE": syntax error

/.../framework/model/Database.php:688
/.../sqlite3/code/SQLite3Database.php:188
/.../clockwork/src/DatabaseProxy.php:44
/.../clockwork/src/DatabaseProxy.php:44
/.../clockwork/src/DatabaseProxy.php:44
/.../clockwork/src/DatabaseProxy.php:44
/.../clockwork/src/DatabaseProxy.php:44
/.../clockwork/src/DatabaseProxy.php:44
/.../clockwork/src/DatabaseProxy.php:44
/.../clockwork/src/DatabaseProxy.php:44
/.../clockwork/src/DatabaseProxy.php:44
/.../clockwork/src/DatabaseProxy.php:44
/.../clockwork/src/DatabaseProxy.php:44
/.../clockwork/src/DatabaseProxy.php:44
/.../clockwork/src/DatabaseProxy.php:44
/.../clockwork/src/DatabaseProxy.php:44
/.../framework/model/DB.php:208
/.../framework/model/DatabaseAdmin.php:260
/.../framework/dev/SapphireTest.php:755
/.../framework/dev/SapphireTest.php:232
/.../framework/dev/FunctionalTest.php:81
/.../shop/tests/cart/ShoppingCartControllerTest.php:14
/.../.composer/vendor/phpunit/phpunit/composer/bin/phpunit:63