add super call to Model and remove self.schedule

[quaquel]

2 minor cleanups to the Model class

• explicitly call super so multiple inheritance works correctly
• remove `self.schedule`` because this is deprecated

[github-actions]

Performance benchmarks:

Model	Size	Init time [95% CI]	Run time [95% CI]
BoltzmannWealth	small	🔵 -1.6% [-2.4%, -0.7%]	🔵 -0.3% [-0.5%, -0.1%]
BoltzmannWealth	large	🔵 -1.4% [-1.7%, -1.1%]	🔵 -0.5% [-1.0%, -0.0%]
Schelling	small	🔵 -0.6% [-0.9%, -0.3%]	🔵 -0.4% [-0.5%, -0.2%]
Schelling	large	🔵 -0.4% [-0.9%, -0.0%]	🔵 -0.0% [-0.9%, +0.8%]
WolfSheep	small	🔵 -1.2% [-1.4%, -1.0%]	🔵 -0.3% [-0.5%, -0.2%]
WolfSheep	large	🔵 -1.8% [-2.3%, -1.3%]	🔵 -1.7% [-3.2%, -0.0%]
BoidFlockers	small	🔵 -1.8% [-2.1%, -1.4%]	🔵 -0.8% [-1.5%, -0.1%]
BoidFlockers	large	🔵 -1.5% [-2.2%, -0.7%]	🔵 +0.2% [-0.3%, +0.7%]