Fixing error in bash script for action.yml (changed-benchmark action)

[raynelfss]

There was an error in the action.yml file that caused the files-changed condition to ignore any new python files. This was due to an error in string parsing that was returning an empty string in every case instead of returning the string without the __init__.py The error was fixed by making the steps.changed-benchmarks.outputs.all_changed_and_modified_files a string stored in a variable.