fix loading in-memory catalog (#1725)

Previously `CatalogType` was fetched by key,
`CatalogType[provided_catalog_type.upper()]` (note the bracket)
This PR changes `CatalogType` to be fetched by value,
`CatalogType(provided_catalog_type.lower())` (note the parenthesis)


https://stackoverflow.com/questions/29799235/python-enum-value2member-map-accessor

This fix loading `in-memory` catalog, `load_catalog("catalog",
**{"type": "in-memory"})`.
Previously, `"in-memory"` caused a key error because its key is
`IN_MEMORY`. Note the `-` vs `_`.


https://github.com/apache/iceberg-python/blob/1d24e71041e35e26e126aa4508ed7384e8aa031c/pyiceberg/catalog/__init__.py#L113-L119


We want `in-memory` and not `in_memory` to match spark

https://github.com/apache/iceberg-python/blob/1d24e71041e35e26e126aa4508ed7384e8aa031c/dev/spark-defaults.conf#L35

Author: kevinjqliu

pyiceberg/catalog/__init__.py

@@ -252,7 +252,7 @@ def load_catalog(name: Optional[str] = None, **properties: Optional[str]) -> Cat
 
     catalog_type = None
     if provided_catalog_type and isinstance(provided_catalog_type, str):
-        catalog_type = CatalogType[provided_catalog_type.upper()]
+        catalog_type = CatalogType(provided_catalog_type.lower())
     elif not provided_catalog_type:
         catalog_type = infer_catalog_type(name, conf)
 

tests/catalog/test_base.py

@@ -88,6 +88,10 @@ def given_catalog_has_a_table(
     )
 
 
+def test_load_catalog_in_memory() -> None:
+    assert load_catalog("catalog", type="in-memory")
+
+
 def test_load_catalog_impl_not_full_path() -> None:
     with pytest.raises(ValueError) as exc_info:
         load_catalog("catalog", **{"py-catalog-impl": "CustomCatalog"})