Make example import absolute

[quaquel]

As discussed in #2381, the current relative imports with the examples create a problem. This at least makes things run again by using absolute imports.

[github-actions]

Performance benchmarks:

Model	Size	Init time [95% CI]	Run time [95% CI]
BoltzmannWealth	small	🟢 -6.7% [-7.7%, -5.7%]	🔵 -0.2% [-0.3%, +0.0%]
BoltzmannWealth	large	🔵 -0.3% [-0.7%, +0.2%]	🔵 -1.4% [-2.4%, -0.4%]
Schelling	small	🔵 -1.1% [-1.6%, -0.7%]	🔵 -0.1% [-0.5%, +0.2%]
Schelling	large	🔵 -1.8% [-2.8%, -0.7%]	🟢 -9.9% [-11.6%, -8.1%]
WolfSheep	small	🔵 -2.6% [-2.9%, -2.3%]	🔵 -0.3% [-0.6%, -0.1%]
WolfSheep	large	🔵 -3.6% [-4.4%, -2.7%]	🟢 -11.7% [-12.9%, -10.6%]
BoidFlockers	small	🔵 -1.4% [-2.0%, -0.7%]	🔵 -0.3% [-0.8%, +0.2%]
BoidFlockers	large	🔵 -0.3% [-1.0%, +0.2%]	🔵 -0.4% [-1.2%, +0.3%]

[Corvince]

Thanks for quickly doing this

[EwoutH]

Awesome, let's validate that this works in all our required cases and I will get a new pre-release out tonight.