deno task doesnt use deno binary that it was called with, but rather still uses the one from PATH when deno binary not named deno

[crowlKats]

reproduce:

• from an rc version: deno upgrade --output=./deno_stable

create deno.json with:

{
  "tasks": {
    "v": "deno -V"
  }
}

and then deno -V, ./deno_stable -V, deno task v, and ./deno_stable task v to reproduce