Fix typo in SDL_MIXER_VERSION comment URL

Author: cclauss

.github/workflows/pythonapp.yml

@@ -5,7 +5,7 @@ on: [push, pull_request]
 env:
   FFMPEG_VERSION: "6.0"  # https://ffmpeg.org/releases/
   SDL_VERSION: "2.26.4"  # https://github.com/libsdl-org/SDL/releases
-  SDL_MIXER_VERSION: "2.6.3"  # https://github.com/libsdl-org/SDL_mixer/releasess
+  SDL_MIXER_VERSION: "2.6.3"  # https://github.com/libsdl-org/SDL_mixer/releases
   USE_SDL2_MIXER: "1"
   MACOSX_DEPLOYMENT_TARGET: "10.13"
   MACOSX_DEPLOYMENT_TARGET_ARM: "11.0"