Allow passing in a delta time of 0.0.

[andriyDev]

This lets us get avoidance data even when we freeze time.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.5%. Comparing base (f226113) to head (c6c26c8).

Additional details and impacted files

Files with missing lines	Coverage Δ
crates/bevy_landmass/src/lib.rs	82.7% <ø> (-0.3%)	⬇️
crates/landmass/src/avoidance.rs	95.4% <100.0%> (+<0.1%)	⬆️
crates/landmass/src/avoidance_test.rs	98.8% <100.0%> (ø)