fix(deps): update rust crate gtk to 0.18

Author: renovate[bot]

src-tauri/Cargo.toml

@@ -25,7 +25,7 @@ tauri-plugin-fs-extra = { git = "https://github.com/tauri-apps/plugins-workspace
 tauri-plugin-window-state = { git = "https://github.com/tauri-apps/plugins-workspace", branch = "v1" }
 
 [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
 
 [target.'cfg(target_os = "macos")'.dependencies]