fix(deps): update rust crate gtk to 0.18

Author: renovate[bot]

src-tauri/Cargo.toml

@@ -46,7 +46,7 @@ webview2-com = "0.19"
 windows = { version = "0.39", features = ["Win32_Foundation"] }
 
 [target.'cfg(target_os = "linux")'.dependencies]
-gtk = "0.15"
+gtk = "0.18"
 webkit2gtk = "0.18" # if tauri build fails, make sure to match this version to what we have in tauri
 dialog = "0.3.0"