gh-183: expand list of classifiers (#197)

This improves the display and visibility on PyPI. Have kept them also in
alphabetical order. Fixes #183.

Reviewed-by: Saransh Chopra <saransh0701@gmail.com>
Reviewed-by: Nicolas Tessore

pyproject.toml

@@ -12,9 +12,17 @@ maintainers = [
     {name = "Nicolas Tessore", email = "n.tessore@ucl.ac.uk"},
 ]
 classifiers = [
-    "Programming Language :: Python :: 3",
     "License :: OSI Approved :: MIT License",
     "Operating System :: OS Independent",
+    "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",
+    "Programming Language :: Python :: 3.12",
+    "Topic :: Scientific/Engineering :: Astronomy",
+    "Topic :: Scientific/Engineering :: Physics",
 ]
 dependencies = [
     "numpy>=1.20.0",