update pyproject.toml, add a .gitignore file

[s-sajid-ali]

Motivation behind unifying everything in pyproject.toml

Adding this as a project via uv raises the following exception:

sh-5.1$ uv add git+https://github.com/coldfront/coldfront-slurm-plugin         
    Updated https://github.com/coldfront/coldfront-slurm-plugin (fb661fbf910bb18e00ef93571c6551585cd522a0)
error: `pyproject.toml` does not match the required schema. When the `[project]` table is present, `project.name` must be present and non-empty.
  Caused by: TOML parse error at line 4, column 5
  |
4 |     "git+https://github.com/coldfront/slurm-python-sdk.git",
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
URL requirement must be preceded by a package name. Add the name of the package before the URL (e.g., `package_name @ https://...`).
git+https://github.com/coldfront/slurm-python-sdk.git
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
sh-5.1$ 

However, adding a skeleton project section is not enough as we then run into more issues as each missing field then raises a separate issue. Now that Coldfront itself uses uv, we should be able to safely drop support for legacy build tools and do away with setup.cfg. Since Coldfront uses, hatch as the build backend, re-use it here instead of adding a new one.

Additional changes:

Change the name of the dependency to slurmrest_python to address:

╰─▶ Package metadata name `slurmrest-python` does not match given name `slurm-python-sdk` 

Set the name of the project to the folder within src to prevent this issuer:

ValueError: Unable to determine which files to ship inside the wheel using the following heuristics:
https://hatch.pypa.io/latest/plugins/builder/wheel/#default-file-selection

Finally, also add a standard .gitignore file for Python from https://github.com/github/gitignore/blob/main/Python.gitignore