chore: Remove single quotes from RSS_FEEDS value in .env_example.

Author: tosaki

.env_example

@@ -23,5 +23,5 @@ RANKING_WINDOW_HOURS=72 # How many hours of news to include in the ranking list
 # HTTPS_PROXY=http://127.0.0.1:7890
 
 # RSS Feeds (JSON Array)
-RSS_FEEDS='["https://spaceflightnow.com/feed/", "https://hnrss.org/newest?points=100"]'
+RSS_FEEDS=["https://spaceflightnow.com/feed/", "https://hnrss.org/newest?points=100"]