Update mime XML

Based on https://github.com/flathub/edu.mit.Scratch/blob/master/edu.mit.Scratch.mime.xml
Fixes .sb3 icon when using flatpak on LMDE

linux-files/org.turbowarp.TurboWarp.mime.xml

@@ -1,15 +1,23 @@
 <?xml version="1.0" encoding="utf-8"?>
 <mime-info xmlns="http://www.freedesktop.org/standards/shared-mime-info">
  <mime-type type="application/x.scratch.sb3">
+ <sub-class-of type="application/zip"/>
  <glob pattern="*.sb3" />
- <icon name="org.turbowarp.TurboWarp" />
+ <comment>Scratch 3 Project</comment>
+ <acronym>SB3</acronym>
+ <generic-icon name="org.turbowarp.TurboWarp" />
  </mime-type>
  <mime-type type="application/x.scratch.sb2">
+ <sub-class-of type="application/zip"/>
  <glob pattern="*.sb2" />
- <icon name="org.turbowarp.TurboWarp" />
+ <comment>Scratch 2 Project</comment>
+ <acronym>SB2</acronym>
+ <generic-icon name="org.turbowarp.TurboWarp" />
  </mime-type>
  <mime-type type="application/x.scratch.sb">
  <glob pattern="*.sb" />
- <icon name="org.turbowarp.TurboWarp" />
+ <comment>Scratch 1 Project</comment>
+ <acronym>SB</acronym>
+ <generic-icon name="org.turbowarp.TurboWarp" />
  </mime-type>
 </mime-info>