Modbus4mqtt

This release adds support for more modbus connection variants (See Modbus variants section in readme), enables global configuration of the unit and write function codes modbus instructions (Thanks M4GNV5 for those improvements!), and pins paho-mqtt to below v2 to avoid breaking API changes (Thanks to cheak1974 for reporting).

This release sets an upper bounds on the version of pymodbus, as there were breaking changes in v3.0.0. It also includes changes to handle the new changes, however these won't have any effect yet. I'll release a v0.6.2 once https://github.com/rpvelloso/Sungrow-Modbus/pull/9 is merged, which fixes the same problem in a modbus4mqtt dependency and I can remove the pymodbus<3.0.0 restriction.

This release adds multi-word register type support: uint32, int32, uint64 and int64. It also adds a word_order top-level configuration setting, defaulting to highlow, that defines the order in which a value is distributed across a range of registers. (Thanks icypete !). It also updates the config for the Sungrow SH5k-20 inverter to use the new uint32 register type.

This release candidate adds multi-word register type support: uint32, int32, uint64 and int64. It also adds a `word_order` top-level configuration setting, defaulting to `highlow`, that defines the order in which a value is distributed across a range of registers. (Thanks icypete !)

Update dependency to fix Python 3.10 compatibility.

Add support for providing client/CA certs/keys to enable TLS connections to an MQTT broker. (Thanks iconnor !)