Fix N803 and N806 ruff errors in basic examples

Fix:
- N803 Argument name should be lowercase: 1 occurrence
- N806 Variable in function should be lowercase: 2 occurrences

examples/basic/boltzmann_wealth_model/app.py

@@ -17,7 +17,7 @@ def agent_portrayal(agent):
 
 
 model_params = {
-    "N": {
+    "n": {
         "type": "SliderInt",
         "value": 50,
         "label": "Number of agents:",

examples/basic/boltzmann_wealth_model/model.py

@@ -11,9 +11,9 @@ class BoltzmannWealthModel(mesa.Model):
     highly skewed distribution of wealth.
     """
 
-    def __init__(self, N=100, width=10, height=10):
+    def __init__(self, n=100, width=10, height=10):
         super().__init__()
-        self.num_agents = N
+        self.num_agents = n
         self.grid = mesa.space.MultiGrid(width, height, True)
 
         self.datacollector = mesa.DataCollector(
@@ -39,6 +39,6 @@ def step(self):
     def compute_gini(self):
         agent_wealths = [agent.wealth for agent in self.agents]
         x = sorted(agent_wealths)
-        N = self.num_agents
-        B = sum(xi * (N - i) for i, xi in enumerate(x)) / (N * sum(x))
-        return 1 + (1 / N) - 2 * B
+        n = self.num_agents
+        b = sum(xi * (n - i) for i, xi in enumerate(x)) / (n * sum(x))
+        return 1 + (1 / n) - 2 * b