Fix usage for bump-{formulae,packages}

[sorairolake]

| preserves newlines, so the current usage tries to run FORMULA-2 as a command.

Expected expand results:

brew bump --open-pr --formulae FORMULA-1 FORMULA-2 FORMULA-3

Actual results:

brew bump --open-pr --formulae FORMULA-1
FORMULA-2
FORMULA-3

This actual result is probably unexpected. So, I fix it to use > to fold newlines.

[MikeMcQuaid]

Thanks so much for your first contribution! Without people like you submitting PRs we couldn't run this project. You rock, @sorairolake!