Obfuscated logging in external preprocessing

[jwindhager]

The following lines should be changed to include the original exception potentially raised here: https://github.com/BodenmillerGroup/steinbock/blob/bc10207a5a690254bb4e65089c06004fe3f19b05/steinbock/preprocessing/external.py#L83-L84

For example similar to the following lines: https://github.com/BodenmillerGroup/steinbock/blob/bc10207a5a690254bb4e65089c06004fe3f19b05/steinbock/measurement/intensities.py#L65-L66