package.json: set type to module

Fixes errors like:
```
SyntaxError: Cannot use import statement outside a module
```

Signed-off-by: Jakub Sokołowski <jakub@status.im>

package.json

@@ -1,6 +1,7 @@
 {
   "name": "@waku/root",
   "private": true,
+  "type": "module",
   "workspaces": [
     "packages/byte-utils",
     "packages/interfaces",