Synfig Studio

## Highlights
Features
* Sketch Tool: Added redo functionality for the sketch tool. (https://github.com/synfig/synfig/issues/3661) [studio]
* Converter: Introduced an Absolute Converter for angle/integer/real values. (https://github.com/synfig/synfig/issues/3618) [core] [studio]
* Color Correct Layer: Added a saturation parameter to the Color Correct layer. (https://github.com/synfig/synfig/issues/3641) [core]

Bug Fixes

* Bevel Layer: Added a null check for sub_task to prevent assertion failure when no layers are below. (https://github.com/synfig/synfig/issues/3701) [core]
* Add-Skeleton-Simple Plugin: Corrected the switched naming of "forearm" and "arm". (https://github.com/synfig/synfig/issues/3687) [studio]
* Gaussian Blur: Fixed the vertical pass for gaussian blur. (https://github.com/synfig/synfig/issues/3682) [core]

Refactoring & Chores

* Avoided copying variable on left-rotating vector. (https://github.com/synfig/synfig/issues/3585) [core]
* Removed CanvasView methods unused since 2005. (https://github.com/synfig/synfig/issues/3679) [studio]
* Fixed synfig::filesystem::Path test for compare method. (https://github.com/synfig/synfig