[inform] edx-platform PRs temporarily broken with mysql check failure

[inform] edx-platform PRs are failing the “Migrations check on MySql 57 / check migrations (ubuntu-20.04, 3.8) (pull_request)” with NameError: name '_mysql' is not defined.

This is being looked into, and we’ll inform again when this is fixed.

[inform] The edx-platform build failures related to mysql and pip.txt has been resolved. Rebase any branches with the latest code to pick up the fix. Thank you!