Update msgspec from 0.20.0 to 0.21.0 (emscripten-forge#5342)

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

Author: emscripten-forge-bot

recipes/recipes_emscripten/msgspec/recipe.yaml

@@ -1,17 +1,17 @@
 context:
   name: msgspec
-  version: 0.20.0
+  version: 0.21.0
 
 package:
   name: ${{ name }}
   version: ${{ version }}
 
 source:
   url: https://pypi.org/packages/source/${{ name[0] }}/${{ name }}/${{ name }}-${{ version }}.tar.gz
-  sha256: 692349e588fde322875f8d3025ac01689fead5901e7fb18d6870a44519d62a29
+  sha256: 9a37c1fb022f895bb24dfac597e449e19eb0cbe62447a832601cb19bb480b51d
 
 build:
-  number: 2
+  number: 0
   script: $PYTHON -m pip install . $PIP_ARGS
 
   files: