all: remove dependency on honnef.co/go/tools (#396)

We actually don't use static check in this repo so this is just
safe to remove.

Fixes: #354
Updates internal bug: b/155334826
diff --git a/go.mod b/go.mod
index 0e29429..a1f0e07 100644
--- a/go.mod
+++ b/go.mod
@@ -8,5 +8,4 @@
 	golang.org/x/tools v0.0.0-20190524140312-2c0ae7006135
 	google.golang.org/grpc v1.27.0
 	google.golang.org/protobuf v1.24.0
-	honnef.co/go/tools v0.0.0-20190523083050-ea95bdfd59fc
 )
diff --git a/tools.go b/tools.go
index 5bb0c29..ae7d6e4 100644
--- a/tools.go
+++ b/tools.go
@@ -27,5 +27,4 @@
 	_ "github.com/golang/protobuf/protoc-gen-go"
 	_ "golang.org/x/lint/golint"
 	_ "golang.org/x/tools/cmd/goimports"
-	_ "honnef.co/go/tools/cmd/staticcheck"
 )