In case I am using YAML file with authentication credentials and setting, I can't set the SOAP_IMPLEMENTATION_KEY (soap_impl) in the file.

googleads.common.LoadFromString and LoadFromStorage support this key and I can change the new default 'zeep' to 'suds'. But unfortunately the googleads.adwords.AdWordsClient._OPTIONAL_INIT_VALUES doesn't allow this option.

This option is very important for running AdWordsClient from serverless environment (specifically AWS Lambda). Zeep tries to create local SQLite files for cache in $HOME (even if I disable cache in client settings). But filesystem is read-only and the application crashes.

It seems to be enough just to add add 'soap_impl' to the list of optional attributes. In this case I can simply specify it in my config. Please advise if I should submit a pull request, or it's enough to report.
Thank you!