Bump decimal to 3.14 (#14017)

Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>

stdlib/_pydecimal.pyi

@@ -1,5 +1,6 @@
 # This is a slight lie, the implementations aren't exactly identical
 # However, in all likelihood, the differences are inconsequential
+import sys
 from _decimal import *
 
 __all__ = [
@@ -41,3 +42,6 @@ __all__ = [
     "HAVE_THREADS",
     "HAVE_CONTEXTVAR",
 ]
+
+if sys.version_info >= (3, 14):
+    __all__ += ["IEEEContext", "IEEE_CONTEXT_MAX_BITS"]