* fixes-for-6607

* Update networkx/algorithms/tests/test_euler.py

Co-authored-by: Mridul Seth <mail@mriduls.com>

* Update euler test

---------

Co-authored-by: Mridul Seth <mail@mriduls.com>
Co-authored-by: Mridul Seth <git@mriduls.com>

* Fix for is_chordal for empty graphs

* Handle self loops case

Replace sets with dict keys to make cycle_basis deterministic with respect
to node ordering.

Co-authored-by: Dan Schult <dschult@colgate.edu>

* Add tests for nx._dispatch decorator

The dispatch functionality is used to delegate graph
computations to a different backend. Because those backends
are not part of NetworkX, testing the dispatching feature
was not originally added, relying instead on the other
backends (e.g. graphblas-algorithms) to verify the dispatch
functionality is working.

This change creates a "loopback" backend where NetworkX dispatches
to itself for the sole purpose of exercising the dispatching
machinery.

In one incarnation, various tests are augmented to use the
LoopbackGraph family and force loopback dispatching to occur
as normal usage would.

A second incarnation forces *all* tests to run in dispatch mode
but use of a different _dispatch decorator. This mode is triggered
for all of pytest, so it must be tested by the CI system specifically.

* Update CI to hopefully run dispatching auto tests

* Formatting

* More formatting fixes

* Better comments explaining dispatching tests

* add simple cycle enumerator for undirected class

* Implemented Gupta & Suzumura and refactored Johnson in a common form
and unified their call-site.  Now, users can enumerate simple cycles
of directed or undireced graphs, with bounded or unbounded length,
all from the same `simple_cycles` function.  I abandoned the stretch
goal of enumerating chordless cycles, as they are not gracefully
handled by the algorithms of Johnson nor Gupta & Suzumura.

* updated tests for simple_cycles to include undirected graphs

* * fixed documentation issues, elaborated on algorithm details
* restricted to nontrivial components
* removed specialized DFS to pick edges from undirected components
    lemma: if G is a biconnected graph with at least 3 nodes and
    e is an edge in G, then e belongs to a cycle

* added tests for undirected and bounded cases for simple_cycles

* added handling for digons in multigraphs

* * Improved support for multigraphs
* Split chordless_cycles out from simple_cycles because the case
  analysis got so tricky
* Added enhanced cycle-testing framework to tests for simple_cycles
* Added tests for multigraphs
* Needs more documentation

* * Documented simple_cycles
* Caught incorrectly-handled case of parallel self-loops

* removed chordless option from simple_cycles

* typos/raises/leftovers in docs and error/corner tests

* add a quick example to chordless_cycles

* Add chordless_cycles to docs

---------

Co-authored-by: Dan Schult <dschult@colgate.edu>
Co-authored-by: Mridul Seth <git@mriduls.com>

* lint and fix using ruff

* add flake8-pie lints

* remove useless import alias

* bump version

* bump deps

---------

Co-authored-by: daniel.eades <daniel.eades@hotmail.com>

* Update developer requirements

* Run linter

* Using create_using

* check edges between cliques

Co-authored-by: Ross Barnowski <rossbar@berkeley.edu>