docs: change 'hello.py' to 'main.py' in python.md (#6319)

A small change to the docs to reflect that `hello.py` has been renamed
to `main.py` in current versions of uv. See

 * astral-sh/uv#10369

Author: my1e5

docs/mise-cookbook/python.md

@@ -55,15 +55,15 @@ Here is how the `uv` project will look like:
 .
 ├── .gitignore
 ├── .python-version
-├── hello.py
+├── main.py
 ├── pyproject.toml
 └── README.md
 
 cat .python-version
 # 3.12
 ```
 
-If you run `uv run hello.py` in the `uv` project, `uv` will automatically create a virtual environment for you using the python version specified in the `.python-version` file. This will also create a `uv.lock` file.
+If you run `uv run main.py` in the `uv` project, `uv` will automatically create a virtual environment for you using the python version specified in the `.python-version` file. This will also create a `uv.lock` file.
 
 `mise` will detect the python version in `.python-version`, however, it won't use the virtual env created by `uv` by default. So, using `which python` will show a global python installation from `mise`.