Add workaround/fix for GGC 12 bound checking error

Issue: pybind#5224

The `internals.registered_types_py...` line in pybind11.h triggers a
false-positive bounds checking warning in GCC 12.

This is discussed in
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115824.

The workaround implemented is taken from suggestions then refactored to
use the `PYBIND11_WARNING_PUSH` and `PYBIND11_WARNING_POP` MACROS.

include/pybind11/pybind11.h

@@ -1380,7 +1380,23 @@ class generic_type : public object {
             } else {
                 internals.registered_types_cpp[tindex] = tinfo;
             }
+#if defined(__GNUG__) && __GNUC__ == 12
+            // The following `GCC diagnostic` pragmas are used to suppress
+            // warnings  about out-of-bounds array access in the following
+            // code. The warnings are false positives. This bug affects GCC 12.
+            //
+            // This is discussed here:
+            // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115824.
+            //
+            // The following fix is based on the the suggested workaround:
+            PYBIND11_WARNING_PUSH
+            PYBIND11_WARNING_DISABLE_GCC("-Wdarray-bounds")
+            PYBIND11_WARNING_DISABLE_GCC("-Wstringop-overread")
+#endif
             internals.registered_types_py[(PyTypeObject *) m_ptr] = {tinfo};
+#if defined(__GNUG__) && __GNUC__ == 12
+            PYBIND11_WARNING_POP
+#endif
         });
 
         if (rec.bases.size() > 1 || rec.multiple_inheritance) {