Telegram now includes a WebView feature when GTK is enabled, which uses www/webkit2-gtk3.
While here, fix the following minor items:
- allow building with Python newer than 3.7
- devel/dee is not needed for build, remove
- clean up USES= syntax in the GTK option
Obtained from: https://github.com/desktop-app/lib_webview/commit/0b4100d7cecc4e748c51f3f51ebfd1392ec3978a
https://github.com/desktop-app/lib_webview/commit/48d70e5258754b2415b07c88f0376212596e09a7
Approved by: ? (maintainer), ? (mentor)
PR: 255719