[3.14] gh-143460: Correct unlimited stack size skip for Emscripten (GH-143765) (#143819)

Modifies the test skip for unlimited stack size to add Emscripten to the
exclusion list.
(cherry picked from commit 1857a40)

Co-authored-by: Russell Keith-Magee <russell@keith-magee.com>

Author: miss-islington

Lib/test/support/__init__.py

@@ -1694,7 +1694,7 @@ def skip_if_unlimited_stack_size(test):
 
     See https://github.com/python/cpython/issues/143460.
     """
-    if is_wasi or os.name == "nt":
+    if is_emscripten or is_wasi or os.name == "nt":
         return test
 
     import resource