fix: Use importlib for polars version (#2952)

Author: dangotbanned

narwhals/_utils.py

@@ -655,7 +655,11 @@ def backend_version(implementation: Implementation, /) -> tuple[int, ...]:
     impl = implementation
     module_name = _IMPLEMENTATION_TO_MODULE_NAME.get(impl, impl.value)
     native_namespace = _import_native_namespace(module_name)
-    if impl.is_sqlframe():
+    if impl.is_polars():
+        from importlib import metadata
+
+        into_version = metadata.version("polars")
+    elif impl.is_sqlframe():
         import sqlframe._version
 
         into_version = sqlframe._version

tests/utils.py

@@ -25,6 +25,8 @@
 
 def get_module_version_as_tuple(module_name: str) -> tuple[int, ...]:
     try:
+        if module_name == "polars":
+            return Implementation.POLARS._backend_version()
         return parse_version(__import__(module_name).__version__)
     except ImportError:
         return (0, 0, 0)