fix hostname validator to accept IPs and hosts with port

[profclems]

Resolves #738

[codecov]

Codecov Report

Merging #744 (659108f) into trunk (cd37ff9) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##            trunk     #744      +/-   ##
==========================================
+ Coverage   58.60%   58.63%   +0.02%     
==========================================
  Files          93       93              
  Lines        6663     6704      +41     
==========================================
+ Hits         3905     3931      +26     
- Misses       2379     2394      +15     
  Partials      379      379              

Impacted Files	Coverage Δ
commands/auth/login/login.go	40.00% <100.00%> (ø)
commands/mr/mrutils/mrutils.go	65.46% <0.00%> (-0.55%)	⬇️

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