update: change meilisearch proximity precision to byAttribute

This setting is more useful for full text search inside paragraphs of content and we already have it at the bottom of our ranking rules. The docs (https://www.meilisearch.com/docs/reference/api/settings#proximity-precision) mention a significant indexing performance boost when this is switched to `byAttribute` so let's take advantage of that.

Requires running `php artisan scout:sync-index-settings`.

config/scout.php

@@ -236,7 +236,8 @@ return [
                     'typo',
                     'proximity',
                 ],
-                'facetSearch' => false,
+                'facetSearch'        => false,
+                'proximityPrecision' => 'byAttribute',
             ],
         ],
     ],