docs: Fix Visualization Tutorial (2.x branch) (#2272)

The scheduler was removed from the example model used, so the docs started failing.

docs/tutorials/visualization_tutorial.ipynb

@@ -43,7 +43,7 @@
     "import mesa\n",
     "\n",
     "# You can either define the BoltzmannWealthModel (aka MoneyModel) or install mesa-models:\n",
-    "%pip install --quiet -U git+https://github.com/projectmesa/mesa-examples#egg=mesa-models\n",
+    "%pip install --quiet -U git+https://github.com/projectmesa/mesa-examples@mesa-2.x#egg=mesa-models\n",
     "\n",
     "from mesa_models.boltzmann_wealth_model.model import BoltzmannWealthModel"
    ]