Improve compatibility with PyPI mirrors that include charset in content-type headers (#261)

* fix: make content-type checking more flexible for PyPI mirrors

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update changelog

* Update changelog

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: MiaowFISH

CHANGELOG.md

@@ -6,6 +6,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Fixed
+
+- Fixed content-type header parsing to handle PyPI mirrors that include charset parameters.
+  This improves compatibility with mirrors that return headers like `application/json; charset=utf-8`.
+  [#261](https://github.com/pyodide/micropip/pull/261)
+
 ## [0.11.0] - 2025/10/18
 
 ### Added

micropip/package_index.py

@@ -250,16 +250,14 @@ def _select_parser(
     """
     Select the function to parse the response based on the content type.
     """
-    match content_type:
+    main_content_type = content_type.split(";")[0].strip()
+
+    match main_content_type:
         case "application/vnd.pypi.simple.v1+json":
             return ProjectInfo.from_simple_json_api
         case "application/json":
             return ProjectInfo.from_json_api
-        case (
-            "application/vnd.pypi.simple.v1+html"
-            | "text/html"
-            | "text/html; charset=utf-8"
-        ):
+        case "application/vnd.pypi.simple.v1+html" | "text/html":
             return partial(
                 ProjectInfo.from_simple_html_api,
                 pkgname=pkgname,