feat: Include superscripts and subscripts in fonts (#463)

## Summary

* Include superscripts and subscripts in fonts

## Additional Context

* Original change came from
https://github.com/crosspoint-reader/crosspoint-reader/pull/248

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### AI Usage

While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
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Did you use AI tools to help write this code? No

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Co-authored-by: cor <cor@pruijs.dev>

lib/EpdFont/scripts/fontconvert.py

@@ -56,6 +56,8 @@ intervals = [
     # Russian, Ukrainian, Bulgarian, etc.
     (0x0400, 0x04FF),
     ### Math Symbols (common subset) ###
+    # Superscripts and Subscripts
+    (0x2070, 0x209F),
     # General math operators
     (0x2200, 0x22FF),
     # Arrows