warnings are captured globally and can be associated to the wrong synop2bufr-process

[maaikelimper]

I noted that warnings can be reported incorrectly when synop2bufr-transform is used by multiple processes in the wis2box-api at the same time, I suspect this is because the warnings are collected from the globally instantiated logger-instances for csv2bufr and pymetdecoder:

https://github.com/wmo-im/synop2bufr/blob/main/synop2bufr/__init__.py#L64-L74