Allow Python 3.8, at the user's risk

PyTables does work with Python 3.8 (whose EOL is on 2024-10 according to
<https://devguide.python.org/versions/>), however we are no longer building
wheels nor testing ourselves (because of dependency wheel availability
issues).  Thus do not reject Python 3.8 straight up, and leave building and
testing up to users or distributions that want to support it.

doc/source/usersguide/installation.rst

@@ -57,7 +57,7 @@ If you don't, fetch and install them before proceeding.
 .. Keep entries from NumPy on in sync with ``project.dependencies`` in ``pyproject.toml``.
 .. Keep system packages in sync with build jobs in `.github/workflows/*.yml`.
 
-* Python_ >= 3.9
+* Python_ >= 3.9 (Python 3.8 may work, but you may need to build/test yourself)
 * HDF5_ >= 1.10.5
 * Cython_ >= 0.29.32
 * NumPy_ >= 1.19.0

pyproject.toml

@@ -26,7 +26,7 @@ description = "Hierarchical datasets for Python"
 # Keep Python versions in sync with
 # `classifiers` below,
 # `min_python_version` in `setup.py`.
-requires-python = ">=3.9"
+requires-python = ">=3.8"
 license = { text = "BSD 3-Clause License" }
 keywords = [ "hdf5" ]
 authors = [
@@ -58,6 +58,7 @@ classifiers = [
     "Programming Language :: Python",
     "Programming Language :: Python :: 3",
     "Programming Language :: Python :: 3 :: Only",
+    "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",

setup.py

@@ -532,7 +532,7 @@ def find_runtime_path(self, locations=None):
 
     # The minimum required versions
     # Keep in sync with ``project.requires-python`` in ``pyproject.toml``.
-    min_python_version = (3, 9)
+    min_python_version = (3, 8)
     # Check for Python
     if sys.version_info < min_python_version:
         exit_with_error("You need Python %s or greater to install PyTables!"