Declare protected properties in WooViet_OnePay_Abstract class to resolve
deprecation warnings when creating dynamic properties in PHP 8.2+.
Properties declared:
- $testmode
- $merchant_id
- $access_code
- $secure_secret
- $user
- $password
- $debug
This fix is backward compatible with older PHP versions and resolves
the warnings reported in issue #94.
Fixes#94
Co-authored-by: Claude <noreply@anthropic.com>
Dat Hoang