Update unstable library feature list by Travis CI build 1511

Author: Travis CI

unstable_library_feature.txt

@@ -185,7 +185,7 @@ int_error_matching                  22639    2020-09-04 13:37:15 +0000  2020-09-
 int_bits_const                      76904    2020-09-04 14:20:01 +0000  2020-09-04 14:20:01 +0000
 unsigned_abs                        74913    2020-09-04 14:20:01 +0000  2020-09-04 14:20:01 +0000
 bufreader_seek_relative             31100    2020-09-10 23:39:55 -0400  2020-09-10 23:39:55 -0400
-slice_check_range                   76393    2020-09-13 12:14:59 +0200  2020-09-13 12:14:59 +0200
+range_bounds_assert_len             76393    2020-09-18 13:55:03 -0400  2020-09-18 13:55:03 -0400
 string_drain_as_str                 76905    2020-09-19 08:23:23 +0200  2020-09-19 08:23:23 +0200
 unsafe_cell_get_mut                 76943    2020-09-19 21:32:33 +0200  2020-09-19 21:32:33 +0200
 unix_socket_peek                    76923    2020-09-19 21:55:01 +0700  2020-09-19 21:55:01 +0700