Fix uneven trailing whitespace in strings

[c42f]

Found as part of https://github.com/JuliaLang/julia/pull/46372 - the reference parser treats lines of uneven whitespace in a weird inconsistent way so there's some differences in whitespace in the final deindented string. This change removes those differences.

[github-actions[bot]]

Try this Pull Request!

Open Julia and type:

  julia> import Pkg
julia> Pkg.activate(temp=true)
julia> Pkg.add(url="https://github.com/c42f/PlutoUI.jl", rev="c42f/fix-uneven-whitespace")
julia> using PlutoUI

Or run this code in your browser:

[fonsp]

Thanks Claire and happy to see you again! 💜

[c42f]

Thanks! :heart: