fix: remove troublesome assertion (#549)

Couple of things going on here:

- Without stac-utils/pystac#1171, the resolved collection won't
  have a root.
- Even with stac-utils/pystac#1171, the root will be cast to a
  `Catalog` by
  https://github.com/stac-utils/pystac/blob/9b363db07f19692d319804ccffce23b72d759839/pystac/stac_object.py#L275-L292,
  so this assertion would fail even with the preserve_dict

To fix breakages to existing code, we remove the assertion, and assume that stuff will
blow up later if the `root` isn't the correct object type.

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### Fixed
+
+- Remove troublesome assertion [#549](https://github.com/stac-utils/pystac-client/pull/549)
+
 ## [v0.7.1] - 2023-06-13
 
 ### Fixed

pystac_client/stac_api_io.py

@@ -267,7 +267,6 @@ def stac_object_from_dict(
             return result
 
         if info.object_type == pystac.STACObjectType.COLLECTION:
-            assert isinstance(root, pystac_client.client.Client)
             return pystac_client.collection_client.CollectionClient.from_dict(
                 d, href=str(href), root=root, migrate=False, preserve_dict=preserve_dict
             )