Merge pull request #84717 from akien-mga/ci-web-emscripten-3.1.39

CI: Pin Emscripten to 3.1.39

.github/workflows/web_builds.yml

@@ -7,7 +7,7 @@ env:
   # Used for the cache key. Add version suffix to force clean build.
   GODOT_BASE_BRANCH: master
   SCONSFLAGS: verbose=yes warnings=extra werror=yes debug_symbols=no
-  EM_VERSION: 3.1.45
+  EM_VERSION: 3.1.39
   EM_CACHE_FOLDER: "emsdk-cache"
 
 concurrency: