tests: Resolve warnings by defining PropertyLayer dtypes

[EwoutH]

Resolve warnings in the space tests by defining PropertyLayer dtypes, by either defining dtype=int or setting the default value from an int (like 1) to a float (like 1.0).

[github-actions]

Performance benchmarks:

Model	Size	Init time [95% CI]	Run time [95% CI]
Schelling	small	🔵 +0.6% [+0.5%, +0.9%]	🔵 +0.4% [+0.3%, +0.6%]
Schelling	large	🔵 -0.4% [-0.7%, -0.0%]	🔵 +0.8% [-0.8%, +2.5%]
WolfSheep	small	🔵 +0.0% [-0.4%, +0.5%]	🔵 +0.0% [-0.1%, +0.1%]
WolfSheep	large	🔵 +0.2% [-0.4%, +0.8%]	🔵 +0.3% [-0.3%, +1.1%]
BoidFlockers	small	🔵 +0.9% [+0.4%, +1.4%]	🔵 +3.0% [+2.3%, +3.8%]
BoidFlockers	large	🔵 +0.5% [+0.2%, +0.8%]	🔴 +4.2% [+3.6%, +4.8%]