Migrate to math/rand/v2 (and by extension Go 1.22)

If this thing can't adopt a new and improved version of the rand package
less than 12 hours after its first stable release, what is it even for?

It's the randomizer. It has one job. And it deserves the best tools the
Go standard library has to offer.

Dockerfile

@@ -1,7 +1,7 @@
 # syntax = docker.io/docker/dockerfile:1.6
 
-ARG ALPINE_BASE=docker.io/library/alpine:3.18
-ARG GOLANG_BASE=docker.io/library/golang:1.21-alpine3.18
+ARG ALPINE_BASE=docker.io/library/alpine:3.19
+ARG GOLANG_BASE=docker.io/library/golang:1.22-alpine3.19
 
 
 FROM --platform=$BUILDPLATFORM $GOLANG_BASE AS build

go.mod

@@ -1,6 +1,6 @@
 module go.alexhamlin.co/randomizer
 
-go 1.21
+go 1.22
 
 require (
 	cloud.google.com/go/firestore v1.14.0

internal/randomizer/app.go

@@ -2,8 +2,7 @@ package randomizer
 
 import (
 	"context"
-	"math/rand"
-	"time"
+	"math/rand/v2"
 )
 
 // Store represents an object that provides persistence for "groups" of
@@ -44,8 +43,7 @@ func NewApp(name string, store Store) App {
 }
 
 func shuffle(options []string) {
-	source := rand.NewSource(time.Now().UnixNano())
-	rand.New(source).Shuffle(len(options), func(i, j int) {
+	rand.Shuffle(len(options), func(i, j int) {
 		options[i], options[j] = options[j], options[i]
 	})
 }