Bump google.golang.org/grpc from 1.37.0 to 1.38.0 in /tools

Bumps [google.golang.org/grpc](https://github.com/grpc/grpc-go) from 1.37.0 to 1.38.0.
- [Release notes](https://github.com/grpc/grpc-go/releases)
- [Commits](grpc/grpc-go@v1.37.0...v1.38.0)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

tools/go.mod

@@ -13,6 +13,6 @@ require (
 	github.com/reviewdog/reviewdog v0.11.0
 	github.com/uber/prototool v1.10.0
 	golang.org/x/tools v0.1.0
-	google.golang.org/grpc v1.37.0
+	google.golang.org/grpc v1.38.0
 	google.golang.org/protobuf v1.25.0
 )

tools/go.sum

@@ -1223,8 +1223,8 @@ google.golang.org/grpc v1.30.0/go.mod h1:N36X2cJ7JwdamYAgDz+s+rVMFjt3numwzf/HckM
 google.golang.org/grpc v1.31.0/go.mod h1:N36X2cJ7JwdamYAgDz+s+rVMFjt3numwzf/HckM8pak=
 google.golang.org/grpc v1.31.1/go.mod h1:N36X2cJ7JwdamYAgDz+s+rVMFjt3numwzf/HckM8pak=
 google.golang.org/grpc v1.32.0/go.mod h1:N36X2cJ7JwdamYAgDz+s+rVMFjt3numwzf/HckM8pak=
-google.golang.org/grpc v1.37.0 h1:uSZWeQJX5j11bIQ4AJoj+McDBo29cY1MCoC1wO3ts+c=
-google.golang.org/grpc v1.37.0/go.mod h1:NREThFqKR1f3iQ6oBuvc5LadQuXVGo9rkm5ZGrQdJfM=
+google.golang.org/grpc v1.38.0 h1:/9BgsAsa5nWe26HqOlvlgJnqBuktYOLCgjCPqsa56W0=
+google.golang.org/grpc v1.38.0/go.mod h1:NREThFqKR1f3iQ6oBuvc5LadQuXVGo9rkm5ZGrQdJfM=
 google.golang.org/protobuf v0.0.0-20200109180630-ec00e32a8dfd/go.mod h1:DFci5gLYBciE7Vtevhsrf46CRTquxDuWsQurQQe4oz8=
 google.golang.org/protobuf v0.0.0-20200221191635-4d8936d0db64/go.mod h1:kwYJMbMJ01Woi6D6+Kah6886xMZcty6N08ah7+eCXa0=
 google.golang.org/protobuf v0.0.0-20200228230310-ab0ca4ff8a60/go.mod h1:cfTl7dwQJ+fmap5saPgwCLgHXTUD7jkjRqWcaiX5VyM=