fix: missing space in template

closes freqtrade#12539

Author: xmatthias

freqtrade/templates/base_config.json.j2

@@ -34,7 +34,7 @@
             "bids_to_ask_delta": 1
         }
     },
-    "exit_pricing":{
+    "exit_pricing": {
         "price_side": "same",
         "use_order_book": true,
         "order_book_top": 1