Fix paths

Replaced backslashes in paths with slashes. I did
not touch function that do the same with paths.
Those can be removed manually.
Also dataDir() returns a path that ends with a
slash so I got rid of duplicated slashes.

src-tauri/tauri.conf.json

@@ -1,5 +1,5 @@
 {
-  "$schema": "..\\node_modules/@tauri-apps/cli\\schema.json",
+  "$schema": "../node_modules/@tauri-apps/cli/schema.json",
   "build": {
     "beforeDevCommand": "yarn start",
     "devPath": "http://localhost:3000",