[REF280] Fix flak8 warnings for src/web_reflectivity

Zhang, Chenrequested to merge
ref280_flake8_src_web_reflectivity into next

Original Gitlab task: https://code.ornl.gov/sns-hfir-scse/reflectometry/reflectometry/-/issues/280

This MR introduces changes that will resolve the flake8 warnings in src/web_reflectivity.

Merge request reports