add allocation check to astronomy_end

[rem1776]

Describe the bug
In astronomy_end there is no allocation check before the deallocation of module variables:

FMS/astronomy/astronomy.F90

Lines 1977 to 1985 in 61cc3b9

	!----------------------------------------------------------------------
	!> deallocate module variables.
	!----------------------------------------------------------------------
	deallocate (orb_angle)
	if (allocated(cosz_ann) ) then
	deallocate (cosz_ann)
	deallocate (fracday_ann)
	deallocate (solar_ann)
	endif

To Reproduce
n/a

Expected behavior
checks should be added for the deallocations

System Environment
n/a

Additional context
came up during mixed precision updates