fix(port): fix host ends with colon but port is empty

[linrongbin16]

This PR fix the parsing error when the host ends with : but port is empty, for example:

ssh://git@github.com:/myorg/terraform-infra.git

Note the host github.com ends with : but the port is empty. See issue: linrongbin16/gitlinker.nvim#250.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.83%. Comparing base (7e9df17) to head (e456c2a).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #36      +/-   ##
==========================================
+ Coverage   95.79%   95.83%   +0.03%     
==========================================
  Files           1        1              
  Lines         214      216       +2     
==========================================
+ Hits          205      207       +2     
  Misses          9        9              

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