ci: close figures before issuing another plot

This prevents `mpl` from warning us about layout changes when tight_layout() gets called twice.

lumicks/pylake/piezo_tracking/tests/test_piezo_tracking.py

@@ -1,5 +1,6 @@
 import pytest
 import numpy as np
+import matplotlib.pyplot as plt
 from lumicks.pylake.channel import Slice, Continuous, TimeSeries
 from lumicks.pylake.piezo_tracking.piezo_tracking import (
     DistanceCalibration,
@@ -83,6 +84,9 @@ def distance1(self):
 def test_plots():
     distance_calibration = DistanceCalibration(*trap_pos_camera_distance(), 1)
     distance_calibration.plot()
+    # Needed since otherwise second plot will issue warning about changing layout (since they both
+    # call tight_layout()
+    plt.close('all')
     distance_calibration.plot_residual()
 
 

lumicks/pylake/population/tests/test_dwelltimes.py

@@ -292,10 +292,12 @@ def test_plots(exponential_data):
     dataset = exponential_data["dataset_2exp"]
     fit = DwelltimeModel(dataset["data"], 1, **dataset["parameters"].observation_limits)
     fit.hist()
+    plt.close('all')
 
     np.random.seed(123)
     bootstrap = fit.calculate_bootstrap(iterations=2)
     bootstrap.hist()
+    plt.close('all')
 
     with pytest.warns(DeprecationWarning):
         bootstrap.plot()