caom2: checksum module alters logging configuration

[grahambell]

The caom2.checksum module reconfigures the standard library logging utility by calling logging.basicConfig() at line 123. This can interfere with the logging options of client applications.

(One specific way this can go wrong is if a client application itself uses logging.basicConfig() after importing the caom2 modules, then the documentation for that function indicates that the second call should do nothing, so the client's logging options don't take effect.) Typically it would only be the application which configures logging rather than libraries also doing so.