https://github.com/gazpachoking/jsonref/commit/f18f30772df086bebdcc9b1b76a35558b4a0a897

Index: pyproject.toml
--- pyproject.toml.orig
+++ pyproject.toml
@@ -37,6 +37,6 @@ profile = "black"
 
 [build-system]
 requires = [
-    "pdm-pep517>=1.0.0",
+    "pdm-backend",
 ]
-build-backend = "pdm.pep517.api"
+build-backend = "pdm.backend"
