fix f-string not formatted

Author: SathyaBhat

source-code/chapter-5/exercise-2/newsbot/reddit.py

@@ -13,7 +13,7 @@ def get_latest_news(sub_reddits):
 
     # Can change the subreddit or add more.
     sub_reddits = clean_up_subreddits(sub_reddits)
-    log.info('Fetching subreddits: {sub_reddits}')
+    log.info(f'Fetching subreddits: {sub_reddits}')
     submissions = r.subreddit(sub_reddits).hot(limit=5)
     submission_content = ''
     try: