gopls: update go.mod for gopls/v0.5.0-pre2

Change-Id: I65b1652b4b6719b6106371698837572362a4ab99
Reviewed-on: https://go-review.googlesource.com/c/tools/+/254557
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
diff --git a/gopls/go.mod b/gopls/go.mod
index 8c0ea07..af2785c 100644
--- a/gopls/go.mod
+++ b/gopls/go.mod
@@ -4,7 +4,7 @@
 
 require (
 	github.com/sergi/go-diff v1.1.0
-	golang.org/x/tools v0.0.0-20200909210919-475d9e863437
+	golang.org/x/tools v0.0.0-20200913034212-796b347e00a4
 	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1
 	honnef.co/go/tools v0.0.1-2020.1.5
 	mvdan.cc/gofumpt v0.0.0-20200802201014-ab5a8192947d