close the file on a tzfile object
close the file on a tzfile object

fixes LP:1376343

Bachmann1234/dateutil,sprymix/python-dateutil,abalkin/dateutil,mjschultz/dateutil,abalkin/dateutil,sprymix/dateutil,pganssle/dateutil-test-codecov,jenshnielsen/dateutil,pganssle/dateutil-test-codecov