Drop support for Python 3.7 and below

Author: AA-Turner

pyproject.toml

@@ -13,7 +13,7 @@ urls.Download = "https://pypi.org/project/sphinxcontrib-htmlhelp/"
 urls.Homepage = "https://www.sphinx-doc.org/"
 urls."Issue tracker" = "https://github.com/sphinx-doc/sphinx/issues"
 license.text = "BSD-2-Clause"
-requires-python = ">=3.6"
+requires-python = ">=3.8"
 
 # Classifiers list: https://pypi.org/classifiers/
 classifiers = [
@@ -27,10 +27,11 @@ classifiers = [
     "Programming Language :: Python",
     "Programming Language :: Python :: 3",
     "Programming Language :: Python :: 3 :: Only",
-    "Programming Language :: Python :: 3.6",
-    "Programming Language :: Python :: 3.7",
     "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",
     "Framework :: Sphinx",
     "Framework :: Sphinx :: Extension",
     "Topic :: Documentation",