Modernize packaging

[cdce8p]

• Move project metadata to pyproject.toml. Remove setup.py file.
• Add SPDX identifier (Apache-2.0) for PEP 639.

Metadata diff

 ...
+License-Expression: Apache-2.0
-Author: Brett Adams
-Author-email: hello@teslemetry.com
+Author-email: Brett Adams <hello@teslemetry.com>
-Home-page: https://github.com/Teslemetry/python-tesla-fleet-api
+Project-URL: Homepage, https://github.com/Teslemetry/python-tesla-fleet-api
 ...
-Classifier: License :: OSI Approved :: Apache Software License
 ...