remove 'tomli' dependency (#1338)

Proposes removing this project's build-time dependency on `tomli`.

It appears to no longer be necessary.

```shell
git grep tomli
```

## Notes for Reviewers

I originally noticed something similar in `ucx-py` (rapidsai/ucx-py#1042), then went searching for similar cases across RAPIDS.

I'm not sure why this project has a dependency on `tomli`, but I suspect it was related to the use of `versioneer` in this project's history. Reference: python-versioneer/python-versioneer#338 (comment)

This project doesn't use `versioneer` any more (#1204). I strongly suspect that the dependency on `tomli` can be removed.

Authors:
  - James Lamb (https://github.com/jameslamb)

Approvers:
  - https://github.com/jakirkham
  - Ray Douglass (https://github.com/raydouglass)

URL: #1338

conda/recipes/dask-cuda/meta.yaml

@@ -29,7 +29,6 @@ requirements:
   host:
     - python
     - pip
-    - tomli
   run:
     - python
     {% for r in data.get("project", {}).get("dependencies", []) %}

dependencies.yaml

@@ -75,9 +75,6 @@ dependencies:
       - output_types: [conda, requirements, pyproject]
         packages:
           - setuptools>=64.0.0
-      - output_types: pyproject
-        packages:
-          - tomli ; python_version < '3.11'
   cuda_version:
     specific:
       - output_types: conda

pyproject.toml

@@ -2,7 +2,6 @@
 build-backend = "setuptools.build_meta"
 requires = [
     "setuptools>=64.0.0",
-    "tomli ; python_version < '3.11'",
 ] # This list was generated by `rapids-dependency-file-generator`. To make changes, edit dependencies.yaml and run `rapids-dependency-file-generator`.
 
 [project]