Fixes #907

Proposed Changes

• adjusted parameter handling during Rescaler instantiation so that now they indeed take an effect when the object is called
• adjusted unit tests - as the new method previously did not care about input parameters, it so happened that default values were able to pass all the tests. However now, when we pass different [min, max] pixel range into in_min_max parameter, it affects the result scaling of the given tensor, even despite out_min_max being set to given threshodl. Given that, tests are updated and now use the real [min, max] range of the random tensor

Checklist

• CONTRIBUTING guide has been followed.
• PR is based on the current GaNDLF master .
• Non-breaking change (does not break existing functionality): provide as many details as possible for any breaking change.
• Function/class source code documentation added/updated (ensure typing is used to provide type hints, including and not limited to using Optional if a variable has a pre-defined value).
• Code has been blacked for style consistency and linting.
• [] If applicable, version information has been updated in GANDLF/version.py.
• [] If adding a git submodule, add to list of exceptions for black styling in pyproject.toml file.
• Usage documentation has been updated, if appropriate.
• Tests added or modified to cover the changes; if coverage is reduced, please give explanation.
• If customized dependency installation is required (i.e., a separate pip install step is needed for PR to be functional), please ensure it is reflected in all the files that control the CI, namely: python-test.yml, and all docker files [1,2,3].