fix(deps): update rust crate gtk to 0.18

Author: renovate[bot]

src-tauri/Cargo.toml

@@ -28,7 +28,7 @@ tauri-plugin-single-instance = { git = "https://github.com/tauri-apps/plugins-wo
 fix-path-env = { git = "https://github.com/tauri-apps/fix-path-env-rs" }
 
 [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]