Temporarily remove nnethercote from the review rotation.

I will be on vacation for the next three weeks. I will re-add myself
when I return.

triagebot.toml

@@ -775,7 +775,6 @@ compiler-team = [
 compiler-team-contributors = [
     "@TaKO8Ki",
     "@Nadrieril",
-    "@nnethercote",
     "@fmease",
     "@fee1-dead",
 ]
@@ -831,17 +830,14 @@ parser = [
     "@compiler-errors",
     "@davidtwco",
     "@estebank",
-    "@nnethercote",
     "@petrochenkov",
     "@spastorino",
 ]
 lexer = [
-    "@nnethercote",
     "@petrochenkov",
     "@estebank",
 ]
 arena = [
-    "@nnethercote",
     "@spastorino",
 ]
 mir = [