fixed bug : Floyd Warshall not working on undirectedEdge graph

[ErikDervishi03]

-this is a pull request for issues #378
this code fix the issue:

if (edge->isDirected() == false) {
  auto reverseKey =
      std::make_pair(elem.second->getUserId(), elem.first->getUserId());
  pairwise_dist[reverseKey] = edgeWeight;
}

this block of code is ensuring that for undirected edges, the pairwise distance map contains entries for both directions in order to have the symmetry of the edges in an undirected graph.
-now all the test works:

[----------] Global test environment tear-down
[==========] 274 tests from 38 test suites ran. (746 ms total)
[  PASSED  ] 274 tests.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (da9c725) 97.52% compared to head (c1994b0) 97.52%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #380   +/-   ##
=======================================
  Coverage   97.52%   97.52%           
=======================================
  Files          55       55           
  Lines        9259     9268    +9     
=======================================
+ Hits         9030     9039    +9     
  Misses        229      229           

Flag	Coverage Δ
unittests	97.52% <100.00%> (+<0.01%)	⬆️

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