Further refine fractional seconds datetimeoffset fixture
Further refine fractional seconds datetimeoffset fixture

in 55f6d61e85b7f16df0b77f1c55a4fb051cd696e3 we still
forgot to accommodate for Python 3 timezone constructor
rejecting fractional minutes so the test further needs lambdas
to prevent the constructor from invoking for Python versions
less than 3.7

Change-Id: I02a83888f5ffbbe53ed0ce16c46a70942add4a3c

graingert/sqlalchemy,j5int/sqlalchemy,j5int/sqlalchemy,monetate/sqlalchemy,zzzeek/sqlalchemy,monetate/sqlalchemy,sqlalchemy/sqlalchemy,graingert/sqlalchemy