Sqlite null fix #1640

Job	Run time
test_bmi_cpp (ubuntu-latest)	2m 39s
test_bmi_cpp (macos-latest)	3m 21s
test_mpi_remote_nexus (ubuntu-latest)	1m 52s
test_pet (ubuntu-latest)	5m 42s
test_pet (macos-latest)	3m 18s
test_unit (ubuntu-latest)	8m 35s
test_bmi_c (ubuntu-latest)	4m 11s
test_unit (macos-latest)	5m 56s
test_bmi_c (macos-latest)	4m 8s
test_bmi_fortran (ubuntu-latest)	3m 51s
test_bmi_fortran (macos-latest)	6m 30s
test_bmi_multi (ubuntu-latest)	4m 5s
test_bmi_multi (macos-latest)	5m 34s
test_bmi_python (ubuntu-latest)	4m 59s
test_bmi_python (macos-latest)	6m 24s
	1h 11m 5s

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