ci: Rename make black* to make format*

[aahung]

Issue #, if available

Description of changes

We use more than black to format our code.

Description of how you validated changes

 ~/P/serverless-application-model ❯❯❯ make black                                                                                                                                           ✘ 130 
Makefile:28: `make black` is deprecated, please use `make format`
# sleep for 5 seconds so the message can be seen.
sleep 5
make format
black setup.py samtranslator tests integration bin schema_source

Checklist

• Adheres to the development guidelines
• Add/update transform tests
  • Using correct values
  • Using wrong values
• Add/update integration tests

Examples?

Please reach out in the comments if you want to add an example. Examples will be
added to sam init through aws/aws-sam-cli-app-templates.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.