Fix database path default (#85)

Before this change, the default for `database_path` would evaluate to
the value that `BITBLAS_DATABASE_PATH` had upon the definition of the
function, ignoring changes made using `set_database_path`.

bitblas/cache/operator.py

@@ -167,7 +167,9 @@ def _instantiate_and_add_operator(self, mapping, config, rt_mod, srcpath, libpat
 global_operator_cache = OperatorCache()
 
 
-def load_global_ops_cache(database_path=BITBLAS_DATABASE_PATH, target=None):
+def load_global_ops_cache(database_path=None, target=None):
+    if database_path is None:
+        database_path = get_database_path()
     if target is None:
         target = bitblas.auto_detect_nvidia_target()
     logger.info(f"Loading operators from database {database_path} for target {target}")