Remove deprecated LJ Aluminum example

examples/mliap/pickle_mliap_unified_lj_Al.py

@@ -1,21 +0,0 @@
-import pickle
-import lammps
-import lammps.mliap
-
-from lammps.mliap.mliap_unified_lj import MLIAPUnifiedLJ
-
-
-if __name__ == '__main__':
-    unified = MLIAPUnifiedLJ()
-    unified.element_types = ["Al"]
-    unified.ndescriptors = 1
-    unified.nparams = 3
-    # Mimicking the LJ pair-style:
-    # pair_style lj/cut 2.5
-    # pair_coeff * * 1 1
-    unified.epsilon = 1.0
-    unified.sigma = 2.5
-    unified.rcutfac = 5.0
-
-    with open('mliap_unified_lj_Al.pkl', 'wb') as fp:
-        pickle.dump(unified, fp)