Draft: exclude Go test files from migrations

[ipoerner]

Database migrations reflect a critical part of an application's workflow. Adding tests for individual migrations following Golang's best practices of reusing the original source file name + appending *_test.go seems to be a reasonable choice.

However, reusing an existing file name that starts with a given numeric value and an underscore will cause problems with Goose, as the migration collector treats it as a regular migrations file, hence failing with:

panic: goose: duplicate version N detected:

This change suggests to blocklist any Go source files ending with the suffix *_test.go in order to mitigate this issue. The naming convention for Go migration files is also mentioned in the README.

[ipoerner]

@mfridman Please excuse me for opening this PR without an issue. I have not found any contrib notes in this repository.

If you think this change is worth getting merged into the main line, I can also add some more tests to migrate.go.

[mfridman]

We already exclude named .go files without a version, so excluding _test.go seems reasonable.

Thanks for filing a PR.