Update element_change.py

[RiesBen]

fix for issue #37

This PR should fix the filter_atoms_h_only_h_mapped bug found by @okbckim

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 96.21%. Comparing base (f371334) to head (0ff2881).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #39 +/- ## ======================================= Coverage 96.21% 96.21% ======================================= Files 13 13 Lines 581 581 ======================================= Hits 559 559 Misses 22 22 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.