Revert "made fixture available in session (#868)" (#870)

This reverts commit d1aa49a.

Author: veenstrajelmer

tests/conftest.py

@@ -10,7 +10,7 @@
 
 
 @pytest.mark.requiressecrets
-@pytest.fixture(scope="session")
+@pytest.fixture
 def file_nc_era5_pattern(tmp_path):
     date_min = '2010-01-31'
     date_max = '2010-02-01'