Update CHANGELOG.md

[Math-Bee]

Summary

Updates the changelog to have more recent information
EDIT:
Forgot to add this, but all I did was copy and paste the new changelog sections from... somewhere else on github (I forgot where T_T). That place didn't have sections for the most recent versions, which is why this updated version only goes up to 9.4.1
EDIT2: The sections are now copied from the releases page; This new updated version now goes to 9.5.2

Tasks Completed

• Platforms Tested:
  • Windows x86
  • Windows ARM
  • macOS x86
  • macOS ARM
  • Linux x86
  • Linux ARM
• Tested For:
  • Basic functionality
  • PyInstaller executable

[CyanVoxel]

Sorry for the delay on getting around to this!
Thank you for the partial update! For reference, the changelogs have been a part of the Releases page since the last time this file was updated. I could merge this now unless you'd be interested in further updating the file with the newer versions

[Math-Bee]

Just added the new parts! A few notes though:

1. I copied everything to the changelog except for the "Still Coming in v9.5.0" and "New Contributors" sections, because I didn't think that they needed to go in a changelog
2. On the 9.5.0 Pre-Release 4 version, the "Fixed" and "Changed" sections had the wrong heading level (h3 instead of h2) so I fixed them here