aider: Updated FileContentCompleter to split files into words on non-alphanums.

# Context:
USER: have FileContentCompleter(Completer) split the files into words on non-alphanums. so each word is a contiguous sequence of alphanums. non-alphanums are ignored, and only used to split.
ASSISTANT: To achieve this, you can update the regular expression used in the `re.split()` function inside the `FileContentCompleter` class. You can use the `\W+` pattern to split the content based on non-alphanumeric characters.

Here's the change:

```python
aider/getinput.py
<<<<<<< ORIGINAL
            for word in re.split(r"\W+", content):
=======
            for word in re.split(r'\W+', content):
>>>>>>> UPDATED
```

This change will ensure that the content is split into words based on non-alphanumeric characters, and each word will be a contiguous sequence of alphanumerics.

aider/getinput.py

@@ -26,7 +26,7 @@ class FileContentCompleter(Completer):
             with open(fname, "r") as f:
                 content = f.read()
 
-            for word in re.split(r"\W+", content):
+            for word in re.split(r'\W+', content):
                 if word.startswith(last_word):
                     yield Completion(word, start_position=-len(last_word))