aider: Added a --completions-height command line parameter to aider/main.py.

# Context:
USER: add a --completions-height cmd line param to `aider/main.py`
ASSISTANT: I will add a `--completions-height` command line parameter to `aider/main.py`. This parameter will allow users to set the height of the completions displayed in the terminal.

Here's the change to add the `--completions-height` parameter:

```python
aider/main.py
<<<<<<< ORIGINAL
    parser.add_argument(
        "--no-dirty-commits",
        action="store_false",
        dest="dirty_commits",
        help="Disable dirty commit of changes",
    )
=======
    parser.add_argument(
        "--no-dirty-commits",
        action="store_false",
        dest="dirty_commits",
        help="Disable dirty commit of changes",
    )
    parser.add_argument(
        "--completions-height",
        type=int,
        default=10,
        metavar="COMPLETIONS_HEIGHT",
        help="Set the height of the completions displayed in the terminal (default: 10)",
    )
>>>>>>> UPDATED
```

This will add a new command line argument `--completions-height` with a default value of 10. Users can now set the height of the completions displayed in the terminal by providing a value for this argument.

aider/main.py

@@ -144,6 +144,13 @@ def main(args=None, input=None, output=None):
         dest="dirty_commits",
         help="Disable dirty commit of changes",
     )
+    parser.add_argument(
+        "--completions-height",
+        type=int,
+        default=10,
+        metavar="COMPLETIONS_HEIGHT",
+        help="Set the height of the completions displayed in the terminal (default: 10)",
+    )
     parser.add_argument(
         "--openai-api-key",
         metavar="OPENAI_API_KEY",