Improve error messaging in CSVReader

[jeremykubica]

Fixes #1023

When CSVReader encounters a file with terminating blank lines and uses the read objects method, it throws a confusing error. This approach wraps the read in a try block and check if the error is just due to blank lines.

Review Checklist for Source Code Changes

• Does pip install still work?
• Have you written a unit test for any new functions?
• Do all the units tests run successfully?
• Does Sorcha run successfully on a test set of input files/databases?
• Have you used black on the files you have updated to confirm python programming style guide enforcement?

[mschwamb]

Looks good to me. Thanks @jeremykubica