Stopgap measures to keep the module limping along

DO NOT USE THIS. IF SOMETHING BREAKS, YOU GET TO KEEP BOTH HALVES. THIS IS A QUICK AND DIRTY HACK.

The endpoint used to submit webforms is deprecated and will stop working in January. It is already unsupported and doesn't give a meaningful result on submission which makes the module report failures despite the submissions actually work. The marketo supplied library has been abandoned and it last changed five years ago which predates the introduction of the new form submit endpoint. It relies on Guzzle 3 which obviously hasn't been updated in a long, long time. Most importantly it doesn't work with PHP 8 but PHP 7.4 is EOL as of 4 days ago.

While a new version of the module is being worked on (thanks!) https://gitlab.com/neclimdul/marketo_ma/ but we need something meanwhile to support the aging codebase.

These patches do so.