Adding support for self hosted gitlab on custom port

[Fahl-Design]

Just a quick fix to support gitlab on custom ports

[codecov]

Codecov Report

Merging #398 (e656405) into master (6c01dce) will decrease coverage by 0.01%.
The diff coverage is 85.71%.

@@             Coverage Diff              @@
##             master     #398      +/-   ##
============================================
- Coverage     99.50%   99.48%   -0.02%     
- Complexity     1848     1850       +2     
============================================
  Files           297      297              
  Lines          5823     5828       +5     
============================================
+ Hits           5794     5798       +4     
- Misses           29       30       +1     

Impacted Files	Coverage Δ	Complexity Δ
...ackageSynchronizer/ComposerPackageSynchronizer.php	97.45% <85.71%> (-0.78%)	35.00 <2.00> (+2.00)	⬇️

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[akondas]

Thanks @Fahl-Design 🍻
We plan to release the new version next Monday or Tuesday.