Battleship Cog Causes IndexError
## Description
<!-- Describe the bug you've found -->
The `battleship` cog runs into an error when given lowercased input. An IndexError is caused when trying to get the matching letter from the list of letters. The bot quits the game with the error:
```
An error occurred. Game failed
```


## Steps to Reproduce
<!-- Detail the exact list of steps to be able to encounter the bug -->
1. Start a game of battleship
2. Send a DM containing any spot in lowercase on your turn (example: `a1`)
3. The bot sends the failure message in the commands channel, the index error is raised to console

## Expected Behaviour
<!-- Outline what you expect to occur, include screenshots if relevant -->
The bot should be able to convert between upper and lower case.


## Actual Behaviour
<!-- Outline what occurs instead of the expected behaviour, include screenshots if relevant -->
The bot errors out on lower case. Error:
```py
File "./sir-lancebot/bot/exts/evergreen/battleship.py", line 146, in get_square
     return grid[number-1][index]  # -1 since lists are indexed from 0
IndexError: list index out of range
```

<!-- ## Known Impacted Platforms -->
<!-- Replace [ ] with [x] to mark items -->
<!-- Seriously? This is a discord bot lol -->

## Possible Solutions
<!-- Detail any solutions you might have in mind to be able to resolve the bug -->
You could try converting from lower to uppercase.

Additionally, you can add a try/except around the input section, to report invalid input and stop the bot from failing the game.


## Would you like to implement a fix?

***Note: For high-priority or critical bugs, fixes may be implemented by staff.***
<!-- Replace [ ] with [x] with your choice -->

- [ ] I'd like to implement the bug fix
- [x] Anyone can implement the bug fix

diff --git a/bot/exts/evergreen/battleship.py b/bot/exts/evergreen/battleship.py
index 9bc374e6..fa3fb35c 100644
--- a/bot/exts/evergreen/battleship.py
+++ b/bot/exts/evergreen/battleship.py
@@ -140,7 +140,7 @@ class Game:
     @staticmethod
     def get_square(grid: Grid, square: str) -> Square:
         """Grabs a square from a grid with an inputted key."""
-        index = ord(square[0]) - ord("A")
+        index = ord(square[0].upper()) - ord("A")
         number = int(square[1:])
 
         return grid[number-1][index]  # -1 since lists are indexed from 0
['bot/exts/evergreen/battleship.py']