STY: solve pylint remarks.

rocketpy/mathutils/function.py

@@ -13,7 +13,6 @@
 from inspect import signature
 from pathlib import Path
 
-import dill
 import matplotlib.pyplot as plt
 import numpy as np
 from scipy import integrate, linalg, optimize

tests/fixtures/hybrid/hybrid_fixtures.py

@@ -1,5 +1,3 @@
-from math import exp
-
 import numpy as np
 import pytest
 

tests/integration/test_flight.py

@@ -5,7 +5,7 @@
 import numpy as np
 import pytest
 
-from rocketpy import Environment, Flight
+from rocketpy import Flight
 
 plt.rcParams.update({"figure.max_open_warning": 0})