Fix :Exclude zero-valued same-spin two-body terms in generate_hamiltonian

[Aniketsy]

#856

This pull request fixes issue by adding a condition to the generate_hamiltonian function that skips the inclusion of two-body Hamiltonian terms with repeated creation .

[mhucka]

Similar to the other PR I just commented on, I recommend running tests locally and debugging the changes locally because that will be easier and faster than waiting for CI checks. This PR currently fails checks; it doesn't look like this code change is correct by itself.