chore(lib): lint and changelog entry

Author: jeertmans

CHANGELOG.md

@@ -15,6 +15,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Added `max_duration_before_split_reverse` and `num_processes` class variables.
   [#439](https://github.com/jeertmans/manim-slides/pull/439)
+- Added `src = ...` filepath argument to allow inserting external
+  videos as slides.
+  [#4526](https://github.com/jeertmans/manim-slides/pull/526)
 
 (unreleased-changed)=
 ### Changed

manim_slides/slide/base.py

@@ -510,7 +510,7 @@ def _add_last_slide(self) -> None:
             )
         )
 
-    def _save_slides(
+    def _save_slides(  # noqa: C901
         self,
         use_cache: bool = True,
         flush_cache: bool = False,