[3.14] pythongh-133644: update Py_InteractiveFlag deprecation notice (pythonGH-133749) (python#133751)

pythongh-133644: update `Py_InteractiveFlag` deprecation notice (pythonGH-133749)
(cherry picked from commit 3ed8d6f)

Co-authored-by: Bénédikt Tran <[email protected]>

Author: miss-islington

Doc/c-api/init.rst

@@ -203,7 +203,7 @@ to 1 and ``-bb`` sets :c:data:`Py_BytesWarningFlag` to 2.
 
    Set by the :option:`-i` option.
 
-   .. deprecated:: 3.12
+   .. deprecated-removed:: 3.12 3.15
 
 .. c:var:: int Py_IsolatedFlag