Release Aseprite v1.3.8.1

What's Changed

• Avoid loading current dithering matrix on each mouse move (related to #4174)
• Fixed New Frame button in the status bar (the little "+" icon) for existing third-party themes #4609
• Windows:
  • Fixed saving files to network paths #4608
  • Fixed File > Export > Export As when exporting files to other drive #4607

Full Changelog: aseprite/aseprite@v1.3.8...v1.3.8.1