Updates species dictionary path for RMG

Updates the species dictionary path to "dictionary.txt" to align with the expected file name for RMG kinetics libraries, whereas thermo uses "species_dictionary.txt".

It appears that RMG, since 3.9, prefers it to be called dictionary.txt

Author: calvinp0

arc/plotter.py

@@ -820,6 +820,7 @@ def save_thermo_lib(species_list: list,
     with open(thermo_file, 'w') as f:
         f.write(thermo_txt)
 
+    # Thermo libraries use species_dictionary.txt.
     species_dict_path = os.path.join(lib_path, 'species_dictionary.txt')
     with open(species_dict_path, 'w') as f:
         for label, adjlist in species_dict.items():
@@ -905,7 +906,8 @@ def save_kinetics_lib(rxn_list: list,
     with open(reactions_file, 'w') as f:
         f.write(reactions_txt)
 
-    species_dict_path = os.path.join(lib_path, 'species_dictionary.txt')
+    # RMG kinetics libraries expect dictionary.txt.
+    species_dict_path = os.path.join(lib_path, 'dictionary.txt')
     with open(species_dict_path, 'w') as f:
         for label, adjlist in species_dict.items():
             f.write(f'{label}\n{adjlist}\n')