Update the tracking issue for const_cstr_from_ptr

Tracking issue rust-lang#101719 was for `const_cstr_methods`, rust-lang#113219 is a new
issue specific for `const_cstr_from_ptr`.

Author: tgross35

library/core/src/ffi/c_str.rs

@@ -256,7 +256,7 @@ impl CStr {
     #[inline]
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_unstable(feature = "const_cstr_from_ptr", issue = "101719")]
+    #[rustc_const_unstable(feature = "const_cstr_from_ptr", issue = "113219")]
     pub const unsafe fn from_ptr<'a>(ptr: *const c_char) -> &'a CStr {
         // SAFETY: The caller has provided a pointer that points to a valid C
         // string with a NUL terminator of size less than `isize::MAX`, whose