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

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

tests/test_single_obs_key.py

@@ -1,7 +1,9 @@
 from ase.build import molecule
 from ase.calculators.singlepoint import SinglePointCalculator
+
 import znh5md
 
+
 def test_single_entry_info(tmp_path):
     # Test a special case where only the first config has the key
     # which caused an error in the past