Load environment variables from a .env file using python-dotenv package.

# Context:
USER: load dotenv
ASSISTANT: To load environment variables from a `.env` file using the `python-dotenv` package, you can add the following lines at the beginning of the `main()` function in the `coder.py` file:

```python
import os
from dotenv import load_dotenv

load_dotenv()
```

You will also need to install the `python-dotenv` package if you haven't already. You can install it using pip:

```
pip install python-dotenv
```

Here's the change to the `coder.py` file:

```python
coder.py
<<<<<<< ORIGINAL
def main():
    env_prefix = "CODER_"
=======
import os
from dotenv import load_dotenv

def main():
    load_dotenv()
    env_prefix = "CODER_"
>>>>>>> UPDATED
```

coder.py

@@ -566,9 +566,12 @@ class Coder:
         return commit_hash, commit_message
 
 
-def main():
+import os
-    env_prefix = "CODER_"
+from dotenv import load_dotenv
 
+def main():
+    load_dotenv()
+    env_prefix = "CODER_"
     parser = argparse.ArgumentParser(description="Chat with GPT about code")
     parser.add_argument(
         "files", metavar="FILE", nargs="+", help="a list of source code files",