Fixes the dme validator erroring on an error for duplicate lines (#73061)

## About The Pull Request

Wouldn't show the actual error due to an error in the throw:
```
Traceback (most recent call last):
  File "P:\goonstation\tools\ci\validate_dme.py", line 92, in <module>
    sorted_lines = sorted(lines, key = functools.cmp_to_key(compare_lines))
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "P:\goonstation\tools\ci\validate_dme.py", line 90, in compare_lines
    raise f"Two lines were exactly the same ({a} vs. {b})"
TypeError: exceptions must derive from BaseException
```

With my change:
```
Traceback (most recent call last):
  File "P:\goonstation\tools\ci\validate_dme.py", line 92, in <module>
    sorted_lines = sorted(lines, key = functools.cmp_to_key(compare_lines))
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "P:\goonstation\tools\ci\validate_dme.py", line 90, in compare_lines
    raise ValueError(f"Two lines were exactly the same ({a} vs. {b})")
ValueError: Two lines were exactly the same (code\serialization.dm vs. code\serialization.dm)
```

I thought about `ImportWarning` but too much work to decide

## Why It's Good For The Game

not broeken

from ur favorite Big Daddy upstream ❤️ 

## Changelog

no

---------

Co-authored-by: Mothblocks <35135081+Mothblocks@users.noreply.github.com>

tools/validate_dme.py

@@ -84,7 +84,8 @@ def compare_lines(a, b):
         if a_segment != b_segment:
             return (a_segment > b_segment) - (a_segment < b_segment)
 
-    raise f"Two lines were exactly the same ({a} vs. {b})"
+    print(f"Two lines were exactly the same ({a} vs. {b})")
+    sys.exit(1)
 
 sorted_lines = sorted(lines, key = functools.cmp_to_key(compare_lines))
 for (index, line) in enumerate(lines):