🩹 add open source Calibri fallback (#51)

see: https://wiki.debian.org/SubstitutingCalibriAndCambriaFonts

Author: meisZWFLZ

themes/radial/rules.typ

@@ -2,7 +2,7 @@
 #import "./colors.typ": *
 
 #let rules(doc) = {
-  set text(font: "Calibri", size: 11pt)
+  set text(font: ("Calibri", "Carlito"), size: 11pt)
   set page("us-letter")
 
   set footnote.entry(separator: none)