Add Black to Spotless check

[khatchad]

Check Python file formatting using Spotless and Black.

• Use print() instead of print.

Black is complaining.

• Format Python code with black.

• Add black to CI.

• Modify black config.

• Format Python files.

• Use Black version 24.1.1.

• Apply spotless.

• Use pip to install Black on Travis CI.

• Upgrade Travis CI top Jammy.

• Use pip to install Black on GH Actions.

• Split Black and Python in GH Actions.

Was getting an error.

• Fix test.

Due to formatting.

• Try requirements.txt.

• Install Python dependencies on GH Actions.

• Explicitly install requirements on Travis CI.

• Change Black config.

• Remove direct Black calls.

[msridhar]

Sorry, what is Black? Can you say more on what this change is doing?

[khatchad]

Sorry, what is Black? Can you say more on what this change is doing?

Sorry, this one is a little hard to see. We're formatting the Python files as well as the XML, Java that is already being formatted by spotless. Black is the Python formatter used by Spotless: https://github.com/psf/black

[khatchad]

Thanks @msridhar. I thought I had changed the pom.xml file in a separate commit to make it more clear but I did not.