unicode: support version 13

[ainar-g]

What version of Go are you using (go version)?

$ go version
go version go1.15 linux/amd64

Does this issue reproduce with the latest release?

Yes.

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/ainar/.cache/go-build"
GOENV="/home/ainar/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/ainar/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/ainar/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/ainar/go/go1.15"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/ainar/go/go1.15/pkg/tool/linux_amd64"
GCCGO="/usr/bin/gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build309808131=/tmp/go-build -gno-record-gcc-switches"

What did you do?

package main

import "unicode"

func main() {
	println(unicode.Version)
}

What did you expect to see?

13.0.0

What did you see instead?

12.0.0

---

I didn't find a recurring issue for Unicode updates, so I decided to submit this one. Please feel free to close if there is one already.

[dmitshur]

/cc @robpike @mpvl per owners.

[ainar-g]

If the process of regenerating the code is documented somewhere, I am ready to try and send a CL myself.

[gopherbot]

Change https://golang.org/cl/248765 mentions this issue: unicode: upgrade to Unicode 13.0.0

[martisch]

I second the question: where is the procedure documented to generate the CL?

My motivation to knowing is not concerned with generating the update CL but more how to change the process to potentially generate more binary size efficient datastructures for the unicode package.