I managed to find the solution. In insert and update I was setting the target.

tanks @Werner Stinckens​ !

delta_df = DeltaTable.forPath(spark, 'dbfs:/mnt/silver/vendas/')                                                   
 
 
delta_df.alias('target').merge(
    source = bronzedf.alias("source"),
    condition = 'target.numero_transacao = source.numero_transacao'
  ) \
  .whenMatchedUpdate(set =
    {
      "numero_transacao": "source.numero_transacao",
      "numped": "source.numped",
      "codcli": "source.codcli",
      "codprod": "source.codprod",
      "data_venda": "source.data_venda",
      "quantidade": "source.quantidade",
      "valor": "source.valor"
      
    }
  ) \
  .whenNotMatchedInsert(values =
    {
      "numero_transacao": "source.numero_transacao",
      "numped": "source.numped",
      "codcli": "source.codcli",
      "codprod": "source.codprod",
      "data_venda": "source.data_venda",
      "quantidade": "source.quantidade",
      "valor": "source.valor"
    }
  ) \
  .execute()