all: release v1.29.1

Change-Id: Ib054f406292d9f2f37e9225d7dd81c65511f43af
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/475876
Reviewed-by: Michael Stapelberg <[email protected]>

Author: lfolger

internal/version/version.go

@@ -52,8 +52,8 @@ import (
 const (
 	Major      = 1
 	Minor      = 29
-	Patch      = 0
-	PreRelease = "devel"
+	Patch      = 1
+	PreRelease = ""
 )
 
 // String formats the version string for this module in semver format.