Go Mysql insert: "Incorrect string value: '\xC3'

Maybe someone from here can help me regarding this problem. I mentioned all details on Stackoverflow - please see here:
https://stackoverflow.com/questions/63767694/go-mysql-insert-incorrect-string-value-xc3

I have tried so far several options and solutions but i am still having the same issue.
I am not sure if its a go- bug? I have no idea.

Would be great to find a way to fix it.
Thank you.