Fix:missing protocol

[JuaniRodriguez]

Summary

GitHub links were being saved in the database without the HTTP/HTTPS protocol.

Details

• Refactor GitHub Link RegExp.

• Refactor variable in test case.

[github-actions]

LCOV of commit 9e72a72 during CI workflow #54

Summary coverage rate:
  lines......: 95.6% (538 of 563 lines)
  functions..: 98.6% (72 of 73 functions)
  branches...: 86.0% (153 of 178 branches)

Files changed coverage rate:
                                                                           |Lines       |Functions  |Branches    
  Filename                                                                 |Rate     Num|Rate    Num|Rate     Num
  ===============================================================================================================
  src/utils/extractLinkFromSubmission.ts                                   |85.7%      7| 100%     1| 100%      1