Remove excess whitespace from end of line to comply with cargo fmt.

[maaku]

My trivial first commit... I noticed that we are almost cargo fmt compliant. There's just two lines with extra whitespace at the end. This PR removes that whitespace.

[hecrj]

Oh, good catch. Thank you!

My editor runs cargo fmt automatically on save, so these were probably introduced by some contributors.

I think it's probably a good idea to check this in CI, at least as a warning for future contributions. Let me see if I can set it up quickly.