Fix for incendiary OB spread. (#4791)

# About the pull request

Followup to #4645.

![image](https://github.com/cmss13-devs/cmss13/assets/4447185/905bb1d9-ef4b-4963-9632-881a7da1bf8c)


# Explain why it's good for the game


![image](https://github.com/cmss13-devs/cmss13/assets/4447185/edd79640-fb51-47b9-baa0-dfd9ca62b86b)

# Changelog
:cl:
fix: Incendiary OB once again spreads to intended size.
/:cl:

code/modules/projectiles/guns/flamer/flamer.dm

@@ -739,7 +739,7 @@ GLOBAL_LIST_EMPTY(flamer_particles)
 		switch(angle) //this reduces power when the explosion is going around corners
 			if (45)
 				spread_power *= 0.75
-			else //turns out angles greater than 90 degrees almost never happen. This bit also prevents trying to spread backwards
+			if (90 to 180) //turns out angles greater than 90 degrees almost never happen. This bit also prevents trying to spread backwards
 				continue
 
 		switch(spread_direction)