message: simplify upgrade command
diff: -import { encode } from "../deps/base64.js";
  import {
  getCurrentVersion,
  getLastDevelopmentVersion,
  @@ -52,20 +51,12 @@ async function install(version: string, dev = false) {
  ? `https://cdn.jsdelivr.net/gh/lumeland/lume@${version}`
  : `https://deno.land/x/lume@${version}`;
  - const importMap = `data:application/json;base64,${
  - encode(`{ "imports": { "lume/": "${url}/" } }`)
  - }`;
  -
  const process = Deno.run({
  cmd: [
  Deno.execPath(),
  - "install",
  - "--unstable",
  - "-Af",
  - `--import-map=${importMap}`,
  - `--no-check`,
  - "--name=lume",
  - `${url}/cli.ts`,
  + "run",
  + "-A",
  + `${url}/install.js`,
  ],
  });
  