Adjust tests for pyodbc 4.0.22

Adjust tests for pyodbc 4.0.22

pyodbc 4.0.22 is no longer allowing a datetime to be truncated
into a date, and additionally is asserting that numeric truncation
is not occurring; previously, it looks like we could send a
decimal of -1E-25 through the driver but we were only getting
back -1E-20, the test failed to check this.  Not clear if the
larger precision worked fully at some point, but in any case,
it doesn't work now so just remove those values from the test.

Change-Id: I66c7863b1708eb72f48173083b4ef78c93893b52