[PR] Add `is_valid_url?` function

[LuchoTurtle]

closes #64

This is a quick merge. Found this useful for small Elixir projects, thanks @ndrean 👌

[codecov[bot]]

Codecov Report

Merging #68 (f329075) into main (335303d) will not change coverage. The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main       #68   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines           50        52    +2     
=========================================
+ Hits            50        52    +2     

Files	Coverage Δ
lib/useful.ex	100.00% <100.00%> (ø)

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[nelsonic]

Agree that checking the validity of a URL is useful. ✅ Just have a quick question in the issue: https://github.com/dwyl/useful/issues/64#issuecomment-1809853290 ❓

If you need this function immeditately, please see: https://hexdocs.pm/link/Link.html#valid?/1 https://github.com/dwyl/link/blob/ca72089c0a56a0e1a96360ccba424b49b8165e3b/lib/link.ex#L143-L161 💭