Rework based on suggested changes

Sphinx 7.1 added the relevant functionality natively.

Author: pradyunsg

python_docs_theme/__init__.py

@@ -4,7 +4,6 @@
 from pathlib import Path
 from typing import Any, Dict, List
 
-import sphinx
 import sphinx.application
 from sphinx.builders.html import StandaloneHTMLBuilder
 
@@ -21,11 +20,6 @@ def _asset_hash(path: str) -> str:
 
 
 def _add_asset_hashes(static: List[str], add_digest_to: List[str]) -> None:
-    if sphinx.version_info >= (7, 1):
-        # https://github.com/sphinx-doc/sphinx/pull/11415 added the relevant
-        # functionality to Sphinx, so we don't need to do anything.
-        return
-
     for asset in add_digest_to:
         index = static.index(asset)
         static[index].filename = _asset_hash(asset)  # type: ignore
@@ -43,7 +37,7 @@ def _html_page_context(
 
     assert isinstance(app.builder, StandaloneHTMLBuilder)
 
-    if sphinx.version_info >= (4,) and "css_files" in context:
+    if (4,) <= sphinx.version_info < (7, 1) and "css_files" in context:
         if "_static/pydoctheme.css" not in context["css_files"]:
             raise ValueError(
                 "This documentation is not using `pydoctheme.css` as the stylesheet. "