Update libheif from 1.21.1 to 1.21.2 (#4264)

Co-authored-by: emscripten-forge-bot <emscripten-forge-bot@users.noreply.github.com>

Author: emscripten-forge-bot

recipes/recipes_emscripten/libheif/recipe.yaml

@@ -1,14 +1,14 @@
 context:
   name: libheif
-  version: 1.21.1
+  version: 1.21.2
 
 package:
   name: ${{ name }}
   version: ${{ version }}
 
 source:
   url: https://github.com/strukturag/libheif/releases/download/v${{ version }}/libheif-${{ version }}.tar.gz
-  sha256: 9799b4b1c19006f052bcf399c761cc147e279762683cefaf16871dbb9b4ea2a1
+  sha256: 75f530b7154bc93e7ecf846edfc0416bf5f490612de8c45983c36385aa742b42
 
 build:
   number: 0