fix: Render agent marker radius correctly

[rht]

Previously, on a 2x20 Schelling grid (extremely tall on the vertical direction, but thin on horizontal direction)

With this PR

[github-actions]

Performance benchmarks:

Model	Size	Init time [95% CI]	Run time [95% CI]
Schelling	small	🔵 +1.5% [+0.7%, +2.2%]	🔵 +2.5% [+2.1%, +3.0%]
Schelling	large	🔵 +1.0% [-0.4%, +2.6%]	🔵 +1.4% [+0.5%, +2.4%]
WolfSheep	small	🔵 +0.2% [-1.5%, +1.9%]	🔵 -0.0% [-0.9%, +0.8%]
WolfSheep	large	🔵 -0.3% [-1.6%, +1.1%]	🔵 -0.4% [-1.2%, +0.5%]
BoidFlockers	small	🔵 -0.7% [-2.9%, +1.3%]	🔵 -0.0% [-0.6%, +0.6%]
BoidFlockers	large	🔵 +0.6% [-1.4%, +3.0%]	🔵 +0.6% [-0.3%, +1.5%]

[EwoutH]

Should this be backported to 2.3?

[rht]

Yeah, sounds good to me.