Make everything more consistent to 3.13

Author: ben-edna

.devcontainer/Dockerfile

@@ -17,7 +17,7 @@ RUN useradd -m dev && chown -R dev:dev /workspaces/dfetch
 USER dev
 
 ENV PATH="/home/dev/.local/bin:${PATH}"
-ENV PYTHONPATH="/home/dev/.local/lib/python3.12"
+ENV PYTHONPATH="/home/dev/.local/lib/python3.13"
 ENV PYTHONUSERBASE="/home/dev/.local"
 
 COPY --chown=dev:dev . .

.readthedocs.yml

@@ -16,7 +16,7 @@ formats:
 build:
   os: ubuntu-22.04
   tools:
-    python: "3.12"
+    python: "3.13"
 
 # Optionally set the version of Python and requirements required to build your docs
 python:

doc/contributing.rst

@@ -19,7 +19,7 @@ and install all runtime dependencies from ``pyproject.toml``.
 
     script/create_venv.py
 
-.. important :: *dfetch* is primarily developed with python 3.12
+.. important :: *dfetch* is primarily developed with python 3.13
 
 Running in Github Codespaces
 ----------------------------

script/create_venv.py

@@ -1,15 +1,32 @@
-#!/usr/bin/env python3.12
+#!/usr/bin/env python3
 """Script to setup a venv."""
 
 import argparse
 import pathlib
 import subprocess  # nosec
+import sys
 import venv
 from typing import Any
 
 PROJECT_ROOT = pathlib.Path(__file__).resolve().parent.parent
 
 
+MIN_VERSION = (3, 9)  # minimum supported; change if needed
+RECOMMENDED_VERSION = (3, 13)  # preferred for development
+
+
+if sys.version_info[:2] < MIN_VERSION:
+    raise RuntimeError(
+        f"⚠ Unsupported Python version {sys.version_info.major}.{sys.version_info.minor}. "
+        f"Please use Python {MIN_VERSION[0]}.{MIN_VERSION[1]} or newer."
+    )
+if sys.version_info[:2] != RECOMMENDED_VERSION:
+    print(
+        f"⚠ Warning: Running with Python {sys.version_info.major}.{sys.version_info.minor}, "
+        f", dfetch is primarily developed with Python {RECOMMENDED_VERSION[0]}.{RECOMMENDED_VERSION[1]}."
+    )
+
+
 class MyEnvBuilder(venv.EnvBuilder):
     """Create a virtual environment.