fix(BudgetTerm.f90): ensure that the size of an array is >0 before deallocating

[emorway-usgs]

• Fix offered in BudgetTerm was discovered using models that included only a single SFT/SFE reach. Previously, GWF models with a single SFR reach would work. Only transport models would fail.
• 2 new autotests offered that each use only a single reach
  • The first autotest is for a GWT model (test_gwt_uztmvt2x1). This test ensures that in addition to a single reach, a single MVT connection between UZT and SFT works as expected
  • The 2nd autotest is for a GWE model (test_gwe_drycell_cnd3). This test checks that conduction between SFE and a dry host cell is working as expected in a single-reach model
• Extended an existing single-reach SFR autotest to include SFT. Prior to this fix, the added GWT model with a single SFT reach would fail because of the bug.
• Brief description of bug offered in release notes
• fprettify
• black