Update pyproject.toml

Fixing this error when installing via `pipx`:

```
× Getting requirements to build wheel did not run successfully.
│ exit code: 1
╰─> [87 lines of output]
configuration error: `tool.setuptools.package-data` keys must be named by:

at least one of the following:
- {type: string, format: 'python-module-name'}
- {predefined value: '*'}

DESCRIPTION:
Mapping from package names to lists of glob patterns. Usually this option is
not needed when using ``include-package-data = true`` For more information
on how to include data files, check ``setuptools`` `docs
<https://setuptools.pypa.io/en/latest/userguide/datafiles.html>`_.

GIVEN VALUE:
{
"sample-exclude.txt": [
"sage"
]
}

OFFENDING RULE: 'propertyNames'
```

pyproject.toml

@@ -67,7 +67,7 @@ sage-index = "sage.index:main"
 sage-chat = "sage.chat:main"
 
 [tool.setuptools.package-data]
-"sample-exclude.txt" = ["sage"]
+"sage" = ["sample-exclude.txt"]
 
 [tool.setuptools.packages]
 find = {}