np.mat error using pyMBE

While running the pyMBE [tutorial](https://github.com/pyMBE-dev/pyMBE/blob/main/tutorials/pyMBE_tutorial.ipynb) the notebook notified me that `np.mat()` is depreciated in numpy and replaced by `np.asmatrix()`. Short check of the numpy 2.0 docs didn't show a `np.mat()` function anymore.

src/python/espressomd/visualization.py

@@ -2887,6 +2887,6 @@ def update_modelview(self):
 
         self.modelview = trans.dot(rotate_cam.dot(trans_cam))
 
-        c_xyz = -1 * np.mat(self.modelview[:3, :3]) * \
-            np.mat(self.modelview[3, :3]).T
+        c_xyz = -1 * np.asmatrix(self.modelview[:3, :3]) * \
+            np.asmatrix(self.modelview[3, :3]).T
         self.cam_pos = np.array([c_xyz[0, 0], c_xyz[1, 0], c_xyz[2, 0]])