Update example_trigger_target_dag.py

[brunolucatto]

[fix] Add provide_context=True in order to make kwargs receive the passed message

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[kaxil]

This has been intentionally removed by some awesome work from @Fokko #5990

[brunolucatto]

I understand it was intentionally removed, but without it, the example is not working on my airflow. I was really confused since two weeks ago it worked, so I went to the git page and saw these changes. Then, I tried adding it again and it solved the case.

I don't know if this works in other circumstances, but it should definitely be double-checked.

[kaxil]

Are you installing Airflow from master? Or just using DAGs?

[brunolucatto]

I did not install airflow, I have been using it as a tool at work, making DAGs. Actually, I was looking at these examples because I am a beginner, so it really gave me a hard time to figure out what was wrong.

[kaxil]

I understand the confusion. You should be checking the example DAGs of the version of Airflow you have installed. For example if you have Airflow 1.10.5 installed, you should look at https://github.com/apache/airflow/tree/1.10.5/airflow/example_dags