Explicitly test basic examples

[quaquel]

This is a quick update to test_examples.py for testing the basic examples.

Presently, it only tests if the models run, no further assertions are made about e.g., results. So the main purpose of this type of test is integration testing.

[github-actions]

Performance benchmarks:

Model	Size	Init time [95% CI]	Run time [95% CI]
BoltzmannWealth	small	🔵 -3.6% [-5.0%, -2.1%]	🔵 +0.1% [-0.1%, +0.3%]
BoltzmannWealth	large	🔵 +0.7% [+0.5%, +0.9%]	🔵 -0.1% [-0.6%, +0.6%]
Schelling	small	🔵 +0.1% [-0.2%, +0.5%]	🔵 -1.0% [-1.3%, -0.8%]
Schelling	large	🔵 +0.6% [-0.2%, +1.3%]	🔵 -0.4% [-1.5%, +1.0%]
WolfSheep	small	🔵 +0.9% [+0.8%, +1.1%]	🔵 +1.1% [+1.0%, +1.3%]
WolfSheep	large	🔵 +0.5% [-0.3%, +1.2%]	🔵 +0.8% [-1.1%, +2.5%]
BoidFlockers	small	🔵 +0.6% [-0.0%, +1.3%]	🔵 -0.9% [-1.5%, -0.2%]
BoidFlockers	large	🔵 -0.7% [-1.4%, +0.2%]	🔵 -0.7% [-1.2%, -0.3%]

[EwoutH]

Huge code reduction, same functionality. Love it!