[submodule]: update sairedis (#5772)

* b458e6f 2020-11-02 | [syncd] Disable use bulk api by default (#688) (HEAD, origin/master, origin/HEAD) [Kamil Cudnik]
* d978789 2020-11-01 | [syncd] Set modify redis flag in RedisSelectableChannel (#689) [Kamil Cudnik]
* 5df11f5 2020-11-01 | [syncd] Lower bulk missing api message level from error to info (#687) [Kamil Cudnik]
* dc73a1d 2020-10-30 | [saiplayer] Fix log messages (#686) [Kamil Cudnik]

Signed-off-by: Guohan Lu <lguohan@gmail.com>