Updated maintainers in pyproject.toml (ni#8)

- [x] This contribution adheres to
[CONTRIBUTING.md](https://github.com/ni/nisync-python/blob/main/CONTRIBUTING.md).

### What does this Pull Request accomplish?

Updated maintainers in pyproject.toml to be `NI <[email protected]>`

### Why should this Pull Request be merged?

NI is the maintainer of this project. 

### What testing has been done?

N/A

Signed-off-by: Tyler Krehbiel <[email protected]>

Author: tkrebes

pyproject.toml

@@ -3,7 +3,7 @@ name = "nisync"
 version = "0.1"
 description = "NI-Sync Python API"
 authors = ["NI <[email protected]>"]
-maintainers = ["Tyler Krehbiel <tyler.krehbiel@ni.com>"]
+maintainers = ["NI <opensource@ni.com>"]
 readme = "README.md"
 repository = "https://github.com/ni/nisync-python"
 license = "MIT"