all: release v1.27.0

Change-Id: Id3587f2020fa58a41574e5f2669c9e50568f06e2
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/330870
Trust: Joe Tsai <joetsai@digital-static.net>
Reviewed-by: Damien Neil <dneil@google.com>

Author: dsnet

internal/version/version.go

@@ -52,9 +52,9 @@ import (
 //	10. Send out the CL for review and submit it.
 const (
 	Major      = 1
-	Minor      = 26
+	Minor      = 27
 	Patch      = 0
-	PreRelease = "devel"
+	PreRelease = ""
 )
 
 // String formats the version string for this module in semver format.