testing/mautrix-whatsapp: upgrade to 0.8.4
https://github.com/mautrix/whatsapp/releases/tag/v0.8.4
Fixed the logging patch too since upstream reworked it https://github.com/mautrix/whatsapp/commit/aceadf18e2c2fb0dc62043ca15c1140375c28377
https://github.com/mautrix/whatsapp/releases/tag/v0.8.4
Fixed the logging patch too since upstream reworked it https://github.com/mautrix/whatsapp/commit/aceadf18e2c2fb0dc62043ca15c1140375c28377