feat(cli/lib): use scene background color as default (#160)

* Use scene background color as default

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

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

* Minor changes to feature: Read scene background

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

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

* Small fix for feature "Read bg color"

* chore(ci): add typing ignore

* fix(ci): typo

---------

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

manim_slides/config.py

@@ -8,6 +8,7 @@ from pathlib import Path
 from typing import Dict, List, Optional, Set, Tuple, Union
 
 from pydantic import BaseModel, FilePath, PositiveInt, root_validator, validator
+from pydantic.color import Color
 from PySide6.QtCore import Qt
 
 from .defaults import FFMPEG_BIN
@@ -150,6 +151,7 @@ class PresentationConfig(BaseModel):  # type: ignore
     slides: List[SlideConfig]
     files: List[FilePath]
     resolution: Tuple[PositiveInt, PositiveInt] = (1920, 1080)
+    background_color: Color = "black"
 
     @root_validator
     def animation_indices_match_files(