Add a fix for if a parameter is None in AimsControlIn

For the atomate2's phonon workflow the symmetry handling in FHI-aims
must be turned off for the displaced cells for it to work. Adding that
option here

pymatgen/io/aims/inputs.py

@@ -478,6 +478,8 @@ def get_aims_control_parameter_str(self, key: str, value: Any, fmt: str) -> str:
         Returns:
             str: The line to add to the control.in file
         """
+        if value is None:
+            return ""
         return f"{key:35s}{fmt % value}\n"
 
     def get_content(