fix: use branch name directly

[Jawayria]

$default-branch is only available in workflow-templates so we'll use branch name directly in this workflow

https://stackoverflow.com/questions/64781462/github-actions-default-branch-variable

[codecov-commenter]

Codecov Report

Merging #337 (5cd7dfd) into master (f7160d5) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #337   +/-   ##
=======================================
  Coverage   94.40%   94.40%           
=======================================
  Files          28       28           
  Lines        3004     3004           
  Branches      161      161           
=======================================
  Hits         2836     2836           
  Misses        150      150           
  Partials       18       18           

Flag	Coverage Δ
unittests	94.40% <ø> (ø)

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[DawoudSheraz]

what's the purpose of $default-branch if it is not usable in workflow? Won't this cause a lot of re-edits when the default branches are renamed to main?

[Jawayria]

what's the purpose of $default-branch if it is not usable in workflow? Won't this cause a lot of re-edits when the default branches are renamed to main?

Yes we'll have to make a lot of re-edits in that case. Actually this $default-branch placeholder is used in workflow templates so that when we add a workflow in repo using that workflow template, it automatically gets replaced with default branch name.