aider: Remove unused imports and variable in aider/linter.py to pass pre-commit hooks.

# Aider chat conversation:

USER: I ran this command:

 .git/hooks/pre-commit

And got this output:

[WARNING] Unstaged files detected.
[INFO] Stashing unstaged files to /Users/gauthier/.cache/pre-commit/patch1715981257-12950.
isort....................................................................Failed
- hook id: isort
- files were modified by this hook

Fixing /Users/gauthier/Projects/aider/aider/linter.py

black....................................................................Failed
- hook id: black
- files were modified by this hook

reformatted aider/linter.py

All done! ✨ 🍰 ✨
1 file reformatted.

flake8...................................................................Failed
- hook id: flake8
- exit code: 1

aider/linter.py:1:1: F401 'os' imported but unused
import os
^
aider/linter.py:6:1: F401 'tree_sitter' imported but unused
import tree_sitter
^
aider/linter.py:9:1: F401 'aider.dump.dump' imported but unused
from aider.dump import dump
^
aider/linter.py:21:5: F841 local variable 'language' is assigned to but never used
    language = get_language(lang)
    ^

[WARNING] Stashed changes conflicted with hook auto-fixes... Rolling back fixes...
[INFO] Restored changes from /Users/gauthier/.cache/pre-commit/patch1715981257-12950.

ASSISTANT: Please add `aider/linter.py` to the chat so I can make the necessary changes to fix the issues reported by the pre-commit hooks.

USER: I added these files to the chat: aider/linter.py

ASSISTANT: To fix the issues reported by the pre-commit hooks, we need to:

1. Remove unused imports: `os`, `tree_sitter`, and `dump`.
2. Remove the unused variable `language`.

Here are the *SEARCH/REPLACE* blocks:

aider/linter.py
```python
<<<<<<< SEARCH
import os
import sys
import warnings
from pathlib import Path

import tree_sitter
from grep_ast import TreeContext, filename_to_lang

from aider.dump import dump
=======
import sys
import warnings
from pathlib import Path

from grep_ast import TreeContext, filename_to_lang
>>>>>>> REPLACE
```

aider/linter.py
```python
<<<<<<< SEARCH
    language = get_language(lang)
=======
>>>>>>> REPLACE
```

Now, the file should pass the pre-commit hooks.

aider/linter.py

@@ -1,13 +1,9 @@
-import os
 import sys
 import warnings
 from pathlib import Path
 
-import tree_sitter
 from grep_ast import TreeContext, filename_to_lang
 
-from aider.dump import dump
-
 # tree_sitter is throwing a FutureWarning
 warnings.simplefilter("ignore", category=FutureWarning)
 from tree_sitter_languages import get_language, get_parser  # noqa: E402
@@ -18,7 +14,6 @@ def basic_lint(fname, code):
     if not lang:
         return
 
-    language = get_language(lang)
     parser = get_parser(lang)
 
     tree = parser.parse(bytes(code, "utf-8"))