feat(lib): allow to insert external videos as slides (#526)

* feat(lib): allow to insert external videos as slides

See https://github.com/jeertmans/manim-slides/discussions/520

* chore(lib): lint and changelog entry

* chore: fix PR #

fix

* fix: docs

manim_slides/slide/base.py

@@ -305,7 +305,7 @@ class BaseSlide:
         :param skip_animations:
             Exclude the next slide from the output.
 
-            If `manim` is used, this is also passed to `:meth:`Scene.next_section<manim.scene.scene.Scene.next_section>`,
+            If `manim` is used, this is also passed to :meth:`Scene.next_section<manim.scene.scene.Scene.next_section>`,
             which will avoid rendering the corresponding animations.
 
             .. seealso::
@@ -348,6 +348,11 @@ class BaseSlide:
                 ``manim-slides convert --to=pptx``.
         :param dedent_notes:
             If set, apply :func:`textwrap.dedent` to notes.
+        :param pathlib.Path src:
+            An optional path to a video file to include as next slide.
+
+            The video will be copied into the output folder, but no rescaling
+            is applied.
         :param kwargs:
             Keyword arguments passed to
             :meth:`Scene.next_section<manim.scene.scene.Scene.next_section>`,
@@ -471,6 +476,18 @@ class BaseSlide:
 
             self._current_slide += 1
 
+        if base_slide_config.src is not None:
+            self._slides.append(
+                PreSlideConfig.from_base_slide_config_and_animation_indices(
+                    base_slide_config,
+                    self._current_animation,
+                    self._current_animation,
+                )
+            )
+
+            base_slide_config = BaseSlideConfig()  # default
+            self._current_slide += 1
+
         if self._skip_animations:
             base_slide_config.skip_animations = True
 
@@ -493,7 +510,7 @@ class BaseSlide:
             )
         )
 
-    def _save_slides(
+    def _save_slides(  # noqa: C901
         self,
         use_cache: bool = True,
         flush_cache: bool = False,
@@ -540,7 +557,10 @@ class BaseSlide:
         ):
             if pre_slide_config.skip_animations:
                 continue
-            slide_files = files[pre_slide_config.slides_slice]
+            if pre_slide_config.src:
+                slide_files = [pre_slide_config.src]
+            else:
+                slide_files = files[pre_slide_config.slides_slice]
 
             try:
                 file = merge_basenames(slide_files)