Update tao dependency

[niutech]

This PR updates tao dependency to the latest version 0.26, which depends on gdk-sys 0.18. This should solve the following error:

error: failed to select a version for `gdk-sys`.
    ... required by package `tao v0.18.0`
    ... which satisfies dependency `winit = "^0.18.0"` of package `eframe_tao v0.23.0`
    ... which satisfies dependency `eframe = "^0.23.0"` of package `tauri-egui v0.3.0`
    ... which satisfies git dependency `tauri-egui` of package `my-tauri-app v0.0.0`
versions that meet the requirements `^0.16` are: 0.16.0

the package `gdk-sys` links to the native library `gdk-3`, but it conflicts with a previous package which links to `gdk-3` as well:
package `gdk-sys v0.18.0`
    ... which satisfies dependency `gdk-sys = "^0.18.0"` (locked to 0.18.0) of package `webkit2gtk v2.0.1`
    ... which satisfies dependency `webkit2gtk = "=2.0.1"` (locked to 2.0.1) of package `tauri v2.0.0-beta.13`
    ... which satisfies dependency `tauri = "^2.0.0-beta"` (locked to 2.0.0-beta.13) of package `my-tauri-app v0.0.0`