Switch build system from Hatchling to PDM

Author: justinmayer

pyproject.toml

@@ -98,5 +98,5 @@ force-sort-within-sections = true
 known-first-party = ["pelican"]
 
 [build-system]
-requires = ["hatchling"]
-build-backend = "hatchling.build"
+requires = ["pdm-backend"]
+build-backend = "pdm.backend"