[3.12] gh-112671: Fixing typo in the Macro Docs (GH-112715) (GH-112726)

Replace Py_T_STRING_INLINE with Py_T_STRING_INPLACE
(cherry picked from commit a8ce149)

Co-authored-by: Amioplk <[email protected]>

Author: miss-islington

Doc/c-api/structures.rst

@@ -592,7 +592,7 @@ Macro name                       C type                        Python type
 
    (*): Zero-terminated, UTF8-encoded C string.
    With :c:macro:`!Py_T_STRING` the C representation is a pointer;
-   with :c:macro:`!Py_T_STRING_INLINE` the string is stored directly
+   with :c:macro:`!Py_T_STRING_INPLACE` the string is stored directly
    in the structure.
 
    (**): String of length 1. Only ASCII is accepted.