Handle accuracy data missing the spaces around +/-

The current leaderboard is raising a runtime error when invalid accuracy data is processed. This results in the following stack trace:
Traceback (most recent call last):
File "/home/user/app/app.py", line 292, in <module>
run_update_dataset()
File "/home/user/app/app.py", line 270, in run_update_dataset
update_leaderboard_dataset(rl_env["rl_env"], path_)
File "/home/user/app/app.py", line 212, in update_leaderboard_dataset
mean_reward, std_reward = parse_rewards(accuracy)
File "/home/user/app/app.py", line 175, in parse_rewards
mean_reward = float(parsed[0])
ValueError: could not convert string to float: '1.0000+/-0.00'

Based on this, it seems this data misses the spaces that were expected around "+/-". I updated the logic so it can handle both "+/-" and " +/- ".
I don't know if this is an acceptable change, but I thought to create a PR for it anyway since the current leaderboard is broken.

app.py

@@ -167,14 +167,13 @@ def parse_rewards(accuracy):
     default_reward=-1000
     if accuracy !=  None:
         accuracy = str(accuracy)
-        parsed =  accuracy.split(' +/- ')
-        if len(parsed)>1:
-            mean_reward = float(parsed[0])
-            std_reward =  float(parsed[1])
-        elif len(parsed)==1: #only mean reward   
-            mean_reward = float(parsed[0])
-            std_reward =  float(0)
-             
+        parsed =  accuracy.split('+/-')
+        if len(parsed)>1):
+            mean_reward = float(parsed[0].strip())
+            std_reward =  float(parsed[1].strip())
+        elif len(parsed)==1): #only mean reward
+            mean_reward = float(parsed[0].strip())
+            std_reward =  float(0) 
         else: 
             mean_reward = float(default_std)
             std_reward = float(default_reward)