MAINT: != -> not_equal in hamming distance implementation
TST: spatial: regression test for gh-4290
Merge pull request #3 from larsmans/hamming-unequal-length

TST: spatial: regression test for gh-4290
Merge pull request #4293 from argriffing/improve-hamming-error-message

MAINT: != -> not_equal in hamming distance implementation