Fix: Ignore vendor packages under proto directory

[khanism]

Because of issue https://github.com/helsing-ai/buffrs/issues/200

This was also addressed in the PR https://github.com/helsing-ai/buffrs/pull/224, but decided to checkout from a "fresher" state of the main branch, since some time has passed since last commit and because of https://github.com/helsing-ai/buffrs/pull/224#issuecomment-1956596971.