Fix newly added PANW threat schema, fix error logging, update avro dep

[shaeqahmed]

• Fix newly added PANW threat schema breaking change (url_category_list: string -> list)
• Dont error!() log the whole mutated event on failure to cloudwatch since we sideline the input event and this can be really huge.
• Improve some error string to include the failing log source table name as this is impossible right now
• Note: most of the diff in transformer/main.rs is just whitespace while adding a missing indent in process() lambda fn