relax phx-class-registry dependency version spec

Author: ppolewicz

pyproject.toml

@@ -29,7 +29,7 @@ dependencies = [
     "docutils>=0.18.1",
     "idna~=3.4; platform_system == 'Java'",
     "importlib-metadata>=3.3; python_version < '3.8'",
-    "phx-class-registry>=4.0,<5",
+    "phx-class-registry>=4.0,<6",
     "rst2ansi==0.1.5",
     "tabulate==0.9.0",
     "tqdm>=4.65.0,<5",