changed deletion of nodes from recursive dfs

[brunos252]

Description

Recursive DFS used for finding flows in the Max Flow algorithm was failing when returning from a recursive call for multiple levels. path = path[:-2] simply reassigned the variable inside that function call, and didn't modify the list itself, leaving edges in path that shouldn't be there. del path[-2:] modifies the list at the original address, which is the wanted functionality.

Pull request type

• Bugfix
• Algorithm/Module
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

Related issues

#140

######################################

Reviewer checklist (the reviewer checks this part)

Module/Algorithm

• Core algorithm/module implementation
• Query module implementation
• Unit tests
• End-to-end tests
• Code documentation
• README short description
• Documentation on memgraph/docs

######################################

[antoniofilipovic]

Note, add E2E test for this case before merging it, as noted on Slack by @jmatak