hugo mod vendor: "invalid modules list" error from recently introduced trailing newline in modules.txt

[bep]

OK, I have no idea how/what this comes from, but the last few Hugo docs builds have started to fail on Netlify, after this commit by me:

gohugoio/hugoDocs@03e6660

This is only relevant if you use hugo mod vendor.

[jmooring]

I have no idea how/what this comes from

I'm pretty sure that was me, fixing a conflict using the GitHub UI before merging gohugoio/hugoDocs#2771.

[bep]

Yea, right ... Oh well, can't hurt to make the parser a little more robust.