all: release v1.20.0
all: release v1.20.0

Change-Id: I3bc9d46f836535393059b9a73e8364211eee9e38
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/221783
Reviewed-by: Herbie Ong <86f376bf42b6daa37c768c730acd318ab6855de4@google.com>

protocolbuffers/protobuf-go,protocolbuffers/protobuf-go