Fix bug in remove_node_from_edge()

[nwlandry]

Fixes the error in this example:

H = xgi.Hypergraph()
H.add_edge([1, 2])
H.edges.members()
# [[1, 2]]
H.remove_node_from_edge(0, 2)

raises the error
XGIError: Node 2 not in edge 0

[leotrs]

Thanks. This looks like the product of a bad merge conflict fix.