patch 8.2.3977: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more error messages to errors.h.
diff --git a/src/if_py_both.h b/src/if_py_both.h
index 6d71ac1..b8716fa 100644
--- a/src/if_py_both.h
+++ b/src/if_py_both.h
@@ -538,7 +538,7 @@
 
     if (PyErr_Occurred())
     {
-	emsg(_("E264: Python: Error initialising I/O objects"));
+	emsg(_(e_python_error_initialising_io_object));
 	return -1;
     }