[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Author: pre-commit-ci[bot]

src/parcels/_core/utils/string.py

@@ -1,5 +1,6 @@
 from keyword import iskeyword, kwlist
 
+
 def _assert_str_and_python_varname(name):
     if not isinstance(name, str):
         raise TypeError(f"Expected a string for variable name, got {type(name).__name__} instead.")