Fix for polars 1.33.0 (dtype becoming mandatory)

ci/environment.yml

@@ -18,7 +18,7 @@ dependencies:
   - netcdf4 >=1.5.5,!=1.6.1
   - pandas >=2.1.0
   - pip
-  - polars>=1.24.0
+  - polars>=1.33.0
   - pooch
   - pre-commit
   - pydantic >=2.0

intake_esm/cat.py

@@ -662,8 +662,10 @@ def _read_csv_pl(self) -> FramesModel:
                 .str.replace('^.', '[')  # Replace first/last chars with [ or ].
                 .str.replace('.$', ']')  # set/tuple => list
                 .str.replace(',]$', ']')  # Remove trailing commas
-                .str.replace_all("'", '"')
-                .str.json_decode()  # This is to do with the way polars reads json - single versus double quotes
+                .str.replace_all(
+                    "'", '"'
+                )  # This is to do with the JSON spec- single versus double quotes
+                .str.json_decode(dtype=pl.List(pl.Utf8))
                 for colname in converters.keys()
             ]
         )