Use tomli for Python < 3.11

Author: rgaiacs

repo2docker/buildpacks/pyproject/__init__.py

@@ -6,9 +6,13 @@
 
 import os
 import re
-import tomllib
 from functools import lru_cache
 
+try:
+    import tomllib
+except ImportError:
+    import tomli as tomllib
+
 from ..conda import CondaBuildPack
 
 VERSION_PAT = re.compile(r"\d+(\.\d+)*")

setup.py

@@ -62,7 +62,7 @@ def get_identifier(json):
         "toml",
         "traitlets",
     ],
-    python_requires=">=3.11",
+    python_requires=">=3.9",
     author="Project Jupyter Contributors",
     author_email="[email protected]",
     url="https://repo2docker.readthedocs.io/en/latest/",