Add configuration to disable checking for updates at startup, including checking for theme updates

[WangJincheng4869]

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What would you like to see added?

Automatically checking for updates is a great feature, but due to network issues, the startup speed can be slow, usually exceeding 5 seconds. This problem almost always occurs after restarting the computer, so I can quickly access the terminal by turning off the update detection function during startup, just like opening it for the second time.

I tried using the following configuration, but still encountered slow loading issues.

{
  "upgrade": {
    "notice": false,
    "interval": "87600h",
    "auto": false,
    "source": "cdn"
  },
  "$schema": "https://raw.githubusercontent.com/JanDeDobbeleer/oh-my-posh/main/themes/schema.json",
  "blocks": [
    {
      "alignment": "right",
      "segments": [
        {
          "background": "#003543",
          "foreground": "#ffffff",
          "style": "plain",
          "template": " \ue641 {{ .CurrentDate | date .Format }} ",
          "type": "time"
        },
        {
          "background": "#83769c",
          "foreground": "#ffffff",
          "properties": {
            "always_enabled": true
          },
          "style": "plain",
          "template": " \ueba2 {{ .FormattedMs }} ",
          "type": "executiontime"
        }
      ],
      "type": "rprompt"
    },
    {
      "alignment": "left",
      "segments": [
        {
          "background": "#61AFEF",
          "foreground": "#ffffff",
          "properties": {
            "display_host": false
          },
          "style": "diamond",
          "template": "{{if .Root}} \uf0e7 {{end}}",
          "trailing_diamond": "\ue0b0",
          "type": "session"
        },
        {
          "background": "#C678DD",
          "foreground": "#ffffff",
          "powerline_symbol": "\ue0b0",
          "properties": {
            "folder_icon": "\uf115",
            "folder_separator_icon": " \ue0b1 ",
            "max_depth": 2,
            "style": "agnoster_short"
          },
          "style": "powerline",
          "template": " {{ .Path }} ",
          "type": "path"
        },
        {
          "background": "#95ffa4",
          "foreground": "#193549",
          "powerline_symbol": "\ue0b0",
          "style": "powerline",
          "template": " {{ .HEAD }} ",
          "type": "git"
        }
      ],
      "type": "prompt"
    }
  ],
  "final_space": true,
  "version": 3
}