all: start v1.36.4-devel

Change-Id: I1dab6caf66b989075199944ce8d07fe8e5e4573a
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/643957
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Chressie Himpel <chressie@google.com>

internal/version/version.go

diff --git a/internal/version/version.go b/internal/version/version.go
index 4a39af0..56c5329 100644
--- a/internal/version/version.go
+++ b/internal/version/version.go
@@ -53,7 +53,7 @@
 	Major      = 1
 	Minor      = 36
 	Patch      = 4
-	PreRelease = ""
+	PreRelease = "devel"
 )
 
 // String formats the version string for this module in semver format.