Dialog Username to PlayerHead help

I'm trying to make a datapack that gives the player a PlayerHead of whoever they type but it isn't working (im extremely new to making datapacks so any help at all is appreciated!)
Code:
{
  "type": "minecraft:multi_action",
  "title": "Player Head Giver",
  "body": [
    {
      "type": "plain_message",
      "contents": "Enter the player name to get their head."
    }
  ],
  "inputs": [
    {
      "type": "minecraft:text",
      "key": "username",
      "label": "Player Name:"
    }
  ],
  "actions": [
    {
      "type": "run_command",
      "label": { "text": "Spawn Head" },
      "command": "give @s player_head{profile = ['$(username)']}"
    },
    {
      "type": "close",
      "label": { "text": "Cancel" }
    }
  ]
}