Update lalpulsar/test/python/test_heterodyned_model.py to use earth00-40-DE405.dat.gz

For some reason lalpulsar/test/python/test_heterodyned_model.py is using a mix of 00-19 and 00-40 ephemeris files:

earthephem = os.path.join(os.environ['LAL_TEST_PKGDATADIR'], 'earth00-19-DE405.dat.gz')
sunephem = os.path.join(os.environ['LAL_TEST_PKGDATADIR'], 'sun00-40-DE405.dat.gz')
timefile = os.path.join(os.environ['LAL_TEST_PKGDATADIR'], 'te405_2000-2040.dat.gz')

When I try to change earth00-19-DE405.dat.gz to earth00-40-DE405.dat.gz, however, the test fails on a tolerance assertion:

        # check output matches that from lalapps_pulsar_parameter_estimation_nested
>       assert_allclose(fullsignal.data.data.real, t4output[:,1])
E       AssertionError: 
E       Not equal to tolerance rtol=1e-07, atol=0
E       
E       Mismatch: 10%
E       Max absolute difference: 2.6544426e-34
E       Max relative difference: 3.0438514e-07
E        x: array([-2.005383e-27,  6.157890e-27, -2.949374e-27, -3.871713e-27,
E               6.071607e-27, -8.720673e-28, -5.468817e-27,  5.125788e-27,
E               1.601887e-27, -6.411303e-27])
E        y: array([-2.005383e-27,  6.157891e-27, -2.949374e-27, -3.871713e-27,
E               6.071607e-27, -8.720671e-28, -5.468817e-27,  5.125788e-27,
E               1.601887e-27, -6.411303e-27])

test_heterodyned_model.py:817: AssertionError

Rather than making the tolerance looser, it would be best to re-generate the reference result being compared to.