Fix bug with species defaults (#4083)

* Fix bug with species defaults

NEed to specify the default value properly

* pre-commit auto-fixes

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: tpurcell90

src/pymatgen/io/aims/inputs.py

@@ -584,7 +584,7 @@ def get_content(
                 content += cube.control_block
 
         content += f"{lim}\n\n"
-        species_defaults = self._parameters.get("species_dir", "")
+        species_defaults = self._parameters.get("species_dir", SETTINGS.get("AIMS_SPECIES_DIR", ""))
         if not species_defaults:
             raise KeyError("Species' defaults not specified in the parameters")