all: release v1.36.6

Change-Id: I243fc05412297e360b019555fd15176b8bc52ce6
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/660315
Reviewed-by: Chressie Himpel <chressie@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

Author: stapelberg

internal/version/version.go

@@ -52,8 +52,8 @@ import (
 const (
 	Major      = 1
 	Minor      = 36
-	Patch      = 5
-	PreRelease = "devel"
+	Patch      = 6
+	PreRelease = ""
 )
 
 // String formats the version string for this module in semver format.