dulwich: bump minver to 0.21.5

Author: pmrowla

setup.cfg

@@ -25,7 +25,7 @@ package_dir=
 packages = find:
 install_requires=
     gitpython>3
-    dulwich>=0.20.49
+    dulwich>=0.21.5
     pygit2>=1.10.0
     pygtrie>=2.3.2
     fsspec>=2021.7.0

src/scmrepo/git/backend/dulwich/__init__.py

@@ -614,6 +614,7 @@ def fetch_refspecs(
         from dulwich.errors import NotGitRepository
         from dulwich.objectspec import parse_reftuples
         from dulwich.porcelain import DivergedBranches, check_diverged, get_remote_repo
+        from dulwich.refs import DictRefsContainer
 
         fetch_refs = []
 
@@ -623,7 +624,7 @@ def determine_wants(
         ) -> List[bytes]:
             fetch_refs.extend(
                 parse_reftuples(
-                    remote_refs,
+                    DictRefsContainer(remote_refs),
                     self.repo.refs,
                     os.fsencode(refspecs)
                     if isinstance(refspecs, str)