修复一点小问题 - #23

[ERROR] Unsupported driver [pdo][263] in /Users/marun/code/hyperf-APIJSON/vendor/hyperf/database/src/Connectors/ConnectionFactory.php
[ERROR] #0 /Users/marun/code/hyperf-APIJSON/vendor/hyperf/database/src/Connectors/ConnectionFactory.php(101): Hyperf\Database\Connectors\ConnectionFactory->createConnection('pdo', Object(Closure), 'sys', '', Array)
#1 /Users/marun/code/hyperf-APIJSON/vendor/hyperf/database/src/Connectors/ConnectionFactory.php(53): Hyperf\Database\Connectors\ConnectionFactory->createSingleConnection(Array)
#2 /Users/marun/code/hyperf-APIJSON/vendor/hyperf/db-connection/src/Connection.php(88): Hyperf\Database\Connectors\ConnectionFactory->make(Array)
#3 /Users/marun/code/hyperf-APIJSON/vendor/hyperf/db-connection/src/Connection.php(63): Hyperf\DbConnection\Connection->reconnect()
#4 /Users/marun/code/hyperf-APIJSON/vendor/hyperf/db-connection/src/Pool/DbPool.php(53): Hyperf\DbConnection\Connection->__construct(Object(Hyperf\Di\Container), Object(Hyperf\DbConnection\Pool\DbPool), Array)

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