fix ChatGPT btn selector

[lroolle]

No description provided.

[lencx]

The ChatGPT UI DOM nesting structure changes frequently, so this approach might be more stable:

// ...
const btns = document.querySelectorAll('main form button');
const btn = btns[btns.length - 1];

[ls-jingbo-jin]

I created another approach before seeing this PR.
Both approaches sees okay to me:

const btns = document.querySelectorAll('main form button');
const btn = btns[btns.length - 1];

This one based on the last button is likely always be the submit button

const svg = document.querySelectorAll('svg[class*="icon-2xl"]')[0];
  btn = svg.parentElement;

This one assume upload svg only appears once in the whole page.

[lroolle]

@lencx I like @ls-jingbo-jin's approach, so I'm going to close this PR for now.

[lencx]

The .icon-2xl class is controlled via TailwindCSS. If OpenAI updates the UI, the class name .icon-2xl might change at any time. On the other hand, using form button is not associated with any specific class and, therefore, is less likely to be affected by changes in class names.

[ls-jingbo-jin]

@lencx I see, thanks for the detail about TailwindCSS👍
I have created another PR based on your approach, please check 🙏:
#165