Library is operating inconsistently after recent changes on the Growatt server side

[muppet3000]

This issue is discussed in far more detail here: home-assistant/core#80950

However, for consistency this is where the final fix needs to be implemented.

Since recent changes by Growatt on their server side there now appears to be some checks in place on the User-Agent field used in the sessions when communicating with Growatt. This means that if a User-Agent is not specified then the majority of queries made to the library are rejected/fail.

I am currently running tests on my local devices (detailed on the ticket above) to ensure the fix works, after which I will submit a PR to this library to make it work for everyone.

[indykoning]

The new user agent addition has been released as v1.2.3 🚀