Fix implementation of tensor product for undirected graphs

[derbuihan]

This PR fixes the implementation of tensor product for undirected graphs.

Example:

import networkx as nx

g = nx.path_graph(2)
h = nx.path_graph(2)
r = nx.tensor_product(g, h)

r.edges() # [((0, 0), (1, 1)), ((0, 1), (1, 0))]

However, this calculation in retworkx outputs [((0, 0), (1, 1)), ((1, 1), (0, 0))].
I fixed the tensor product in retworkx to output the same result as networkx.

[coveralls]

Pull Request Test Coverage Report for Build 2265616434

• 18 of 18 (100.0%) changed or added relevant lines in 1 file are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.005%) to 97.194%

---

Files with Coverage Reduction	New Missed Lines	%
src/shortest_path/all_pairs_dijkstra.rs	1	98.54%

Totals
Change from base Build 2265302597:	-0.005%
Covered Lines:	11294
Relevant Lines:	11620

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💛 - Coveralls

[georgios-ts]

Nice catch! Can you also add a release note describing the bug fix?

[derbuihan]

@georgios-ts
Even though tensor product has not been released yet, is it necessary to add the bug fix to relaesenotes?

[georgios-ts]

Yeah, we don't need a release-note. (I got confused and thought we added tensor product in the previous release).
Thanks for the updates!

[CLAassistant]

All committers have signed the CLA.