Copy task fails for tables with `json` columns

[tonbadal]

I'm running a copy task with a table users that contains a metadata column with type json.

tasks:
  copy_users:  
    type: copy
    source:
      db: input_db
      table: users
    destination:
      db: output_db
      table: users

And when running the pipeline I get the following error:

INFO|Run Steps: Prepare Load, Load Data, Move Table
INFO|[1/3]  Executing Prepare Load
INFO|[1/3]  Prepare Load (97.8ms)
INFO|[2/3]  Executing Load Data
ERROR|Failed (2s) invalid input syntax for type json
DETAIL:  Token "'" is invalid.
CONTEXT:  JSON data, line 1: {'...
COPY sayn_tmp_users, line 10, column metadata: "{'title': 'Engineer'}"

I've successfully copied other tables that don't have json columns.

Both input and output databases are PostgreSQL, runnning in Python 3.9.13, SAYN version 0.6.5.

Many thanks in advance!