Secret API Key is logged in cleartext

## Summary: While code-reviewing the repository <https://github.com/omise/omise-python/>, I have found that you log in clear-text some sensitive data. ## Steps To Reproduce: 1. Check here [omise/request.py#L88](https://github.com/omise/omise-python/blob/bfcf283378a823139b9f19f10e84d42a98c5b1ac/omise/request.py#L88) and here [omise/request.py#L111](https://github.com/omise/omise-python/blob/bfcf283378a823139b9f19f10e84d42a98c5b1ac/omise/request.py#L111) 1. The code source explicitly logs in debugging mode the secret API key. ``` logger.debug('Authorization: %s', self.api_key) ``` 1. Activate logging level debug and run the following sample.py file ``` import omise omise.api_secret = 'skey_test_5sqdfyjv0rtqzs9f2x2' customer = omise.Customer.create( description='John Doe', email='[email protected]' ) ``` You will get: {F1857247} ## Impact - sensitive data logged in clear text may end up in unusual places: recorded demonstrations, copied logs, etc. ## Remediation - I suggest you log at least a partial part of the secret API key if not remove the L88 and L111 in whole.