fix(nix/linux): allow tray-icon to compile on linux

[jonknapp]

Not in use since db89109 and keeping it breaks the nix build.

error info

error: Cannot build '/nix/store/y735fgjmwhb65zacwq3jk3vpdlwa940k-vykar-gui-0.20.1.drv'.
       Reason: builder failed with exit code 101.
       Output paths:
         /nix/store/vhf7b1jmqab2a4d5g1f5sdkjix7gjvgm-vykar-gui-0.20.1
       Last 25 log lines:
       >    Compiling accesskit_atspi_common v0.19.1
       >    Compiling atspi v0.29.0
       >    Compiling accesskit_unix v0.22.1
       >    Compiling accesskit_winit v0.33.2
       >    Compiling i-slint-backend-winit v1.17.1
       >    Compiling i-slint-backend-selector v1.17.1
       >    Compiling slint v1.17.1
       > error[E0599]: no method named `with_icon_templated` found for struct `TrayIconBuilder` in the current scope
       >   --> crates/vykar-gui/src/tray.rs:81:10
       >    |
       > 78 |       let tray = TrayIconBuilder::new()
       >    |  ________________-
       > 79 | |         .with_menu(Box::new(menu))
       > 80 | |         .with_tooltip(APP_TITLE)
       > 81 | |         .with_icon_templated(icon)
       >    | |_________-^^^^^^^^^^^^^^^^^^^
       >    |
       > help: there is a method `with_icon_as_template` with a similar name
       >    |
       > 81 -         .with_icon_templated(icon)
       > 81 +         .with_icon_as_template(icon)
       >    |
       >
       > For more information about this error, try `rustc --explain E0599`.
       > error: could not compile `vykar-gui` (bin "vykar-gui") due to 1 previous error
       For full logs, run:
         nix log /nix/store/y735fgjmwhb65zacwq3jk3vpdlwa940k-vykar-gui-0.20.1.drv

[jonknapp]

Ignore this for now. I ran build locally but not specifically for vykar-gui. I'll track down the issue and submit a fix.

[jonknapp]

Additional context while working on a fix:

In tray-icon 0.26.0 and the repository’s main branch:

• with_icon_templated(Icon) exists, but only on macOS.
• Linux and Windows should use with_icon(Icon).
• with_icon_as_template(bool) is deprecated in 0.26.

Updated tray.rs with target-specific builder selection so the Nix/Linux build uses .with_icon(icon), while macOS uses .with_icon_templated(icon).

from the tray-icon changelog, [0.26.0]

930505e (#377 by @amrbashir) Add TrayIcon::set_icon_templated and TrayIconBuilder::with_icon_templated on macOS, which set the icon and draw it as a template image in one call, so the template flag can never be left describing an icon that has since been replaced. Also add TrayIcon::icon_is_template to read that state back.

Deprecate TrayIcon::set_icon_as_template, TrayIcon::set_icon_with_as_template and TrayIconBuilder::with_icon_as_template in favour of them. TrayIcon::set_icon now also clears TrayIconAttributes::icon_is_template, which used to keep saying true for an icon it no longer described. 

• with_icon_templated(icon) is the new API, but macOS-only.
• with_icon_as_template(bool) is deprecated.
• On Linux, use plain with_icon(icon)

The target-specific implementation now follows the changelog and avoids the deprecated API.