test_generate_dictionary_file unit test intermittently fails

[jvendetti]

The test_generate_dictionary_file unit test is intermittently failing on this line:

ncbo_annotator/test/test_annotator.rb

Line 100 in b1593ae

assert refresh_timestamp > start_timestamp

See the following GitHub Action runs for examples:

https://github.com/ncbo/ncbo_annotator/runs/5698818078
https://github.com/ncbo/ncbo_annotator/runs/6068868691

In subsequent commits with no related code changes the test passes. The overall functionality of the Annotator seems unaffected.