Improve CI detection for database migration issues

[mxsasha]

If migrations cause a migration conflict, the testing parts of the build just hang forever with no clear output, e.g. here. Perhaps an easy fix is to check for this in the lint job, also checking that makemigrations is empty, i.e. all changes have a migration.

[bwbroersma]

What is the 'migration conflict'? I had the same in the CI runs of #1319 (which I canceled).

[mxsasha]

What is the 'migration conflict'? I had the same in the CI runs of #1319 (which I canceled).

The most common form: multiple paths. Your new migration depends on 0015_auto_20240212_1616, but 0015_add_rpki_scoring does too. This means Django can't determine the correct order. I should probably have renamed that to 0016_add_rpki_scoring to avoid Django mis-guessing which one to base a new migration on. The fix for you is to depend on 0015_add_rpki_scoring.