fix(date): use available timezone if any #94

98.4% (target 80.0%)

All modified and coverable lines are covered by tests ✅

Files with missing lines	Coverage Δ
handler.go	`100.0% <100.0%> (ø)`
pesticide/time_test_helpers.go	`100.0% <100.0%> (ø)`
registry/conversion/functions.go	`100.0% <100.0%> (ø)`
registry/time/functions.go	`100.0% <100.0%> (ø)`
registry/time/helpers.go	`100.0% <100.0%> (ø)`
sprigin/sprig_backward_compatibility.go	`100.0% <100.0%> (ø)`