### Tasks
- [x] Update `compute_frequency` function in the backend
- [x] Update `discovery.js` file in the frontend to take into account the changes introduced in the backend
- [x] Update `discovery.js` file in the frontend to add overlay statistics on the edges
- [x] Update `discovery.js` file in the frontend to update the styles of edges
Prior to pm4py 2.6.1, it was not possible to get the statistics related to edges from the Petri net corresponding to the BPMN.
The fix has been introduced in 2.6.1: https://github.com/pm4py/pm4py-core/commit/84e85c6e4715fe58159f6cfb83248d1cfa28bc8e
Update the code to take into account this fix.