Uncaught exception in translator when `publication` isn't present in parsed record

[seasidesparrow]

Under certain circumstances (e.g. IEEE) the method _get_publication in translator can be called without there being a publication key present in the parsed record. At L474

ADSManualParser/adsmanparse/translator.py

Line 474 in 96eb6e6

if publisher == 'Zenodo':

there is a check to see if publisher == "Zenodo", but in this case, publisher was never instantiated, which results in an exception.

Fix by adding publisher="" after L386