Ensure only ruby PLATFORM is used

We've been seeing gems are vendored without properly setting the PLATFORM to only ruby.

See an example fix !126000 (merged).

Context:

What linting or CI jobs could we add to ensure that the Gemfile.lock is completely correct before an MR can be merged?

You may need to run rm Gemfile.lock && BUNDLE_FORCE_RUBY_PLATFORM=1 bundle install to properly resolve gems for the ruby PLATFORM and make sure it matches. I didn't confirm if this is the problem here, it looks like there may be other problems in this case. See this recent MR: Use ruby platform for clickhouse vendored gem (!126000 - merged)

What can think we can do to enforce the proper generation/update of Gemfile.lock for vendored gems, so we don't keep running into these problems?

Edited by charlie ablett