This commit fixes an issue with the marginal_distribution() function
where it would previously error if a numpy arrray of ints was passed in
for the indices parameter. This was caused by the input validation
looking for empty input by checking `not indices` which isn't valid for
numpy arrays. This commit fixes this by adjusting the check for
empty lists to work with any sequence input.

Fixes Qiskit#8283

…37d84.yaml

Co-authored-by: Jim Garrison <jim@garrison.cc>