all: start v1.36.6-devel

Change-Id: I2fe82be1a65ae45971d47078368f30d57097b648
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/660316
Reviewed-by: Chressie Himpel <chressie@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
diff --git a/internal/version/version.go b/internal/version/version.go
index aac1cb1..3c91dbb 100644
--- a/internal/version/version.go
+++ b/internal/version/version.go
@@ -53,7 +53,7 @@
 	Major      = 1
 	Minor      = 36
 	Patch      = 6
-	PreRelease = ""
+	PreRelease = "devel"
 )
 
 // String formats the version string for this module in semver format.