Update TFRT dependency to use revision http://github.com/tensorflow/runtime/commit/8868e79e2e605875c577c9fbca54ff8f38894385.
Update TFRT dependency to use revision
http://github.com/tensorflow/runtime/commit/8868e79e2e605875c577c9fbca54ff8f38894385.

PiperOrigin-RevId: 488933985

google/tsl,google/tsl,google/tsl