Remove myself from the libs review queue

I unfortunately don't have the time to devote to reviews here anymore.

Author: sfackler

highfive/configs/rust-lang/rust.json

@@ -12,7 +12,6 @@
             "@davidtwco"
         ],
         "libs": [
-            "@sfackler",
             "@dtolnay",
             "@JoshTriplett",
             "@Mark-Simulacrum",