Fix readthedocs builds

[GrandMoff100]

Running Sphinx v5.3.0

Traceback (most recent call last):
  File "/home/docs/checkouts/readthedocs.org/user_builds/homeassistantapi/envs/129/lib/python3.10/site-packages/sphinx/config.py", line 350, in eval_config_file
    exec(code, namespace)
  File "/home/docs/checkouts/readthedocs.org/user_builds/homeassistantapi/checkouts/129/docs/conf.py", line 17, in <module>
    import toml  # type: ignore[import]
ModuleNotFoundError: No module named 'toml'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/docs/checkouts/readthedocs.org/user_builds/homeassistantapi/envs/129/lib/python3.10/site-packages/sphinx/cmd/build.py", line 276, in build_main
    app = Sphinx(args.sourcedir, args.confdir, args.outputdir,
  File "/home/docs/checkouts/readthedocs.org/user_builds/homeassistantapi/envs/129/lib/python3.10/site-packages/sphinx/application.py", line 202, in __init__
    self.config = Config.read(self.confdir, confoverrides or {}, self.tags)
  File "/home/docs/checkouts/readthedocs.org/user_builds/homeassistantapi/envs/129/lib/python3.10/site-packages/sphinx/config.py", line 172, in read
    namespace = eval_config_file(filename, tags)
  File "/home/docs/checkouts/readthedocs.org/user_builds/homeassistantapi/envs/129/lib/python3.10/site-packages/sphinx/config.py", line 363, in eval_config_file
    raise ConfigError(msg % traceback.format_exc()) from exc
sphinx.errors.ConfigError: There is a programmable error in your configuration file:

Traceback (most recent call last):
  File "/home/docs/checkouts/readthedocs.org/user_builds/homeassistantapi/envs/129/lib/python3.10/site-packages/sphinx/config.py", line 350, in eval_config_file
    exec(code, namespace)
  File "/home/docs/checkouts/readthedocs.org/user_builds/homeassistantapi/checkouts/129/docs/conf.py", line 17, in <module>
    import toml  # type: ignore[import]
ModuleNotFoundError: No module named 'toml'


Configuration error:
There is a programmable error in your configuration file:

Traceback (most recent call last):
  File "/home/docs/checkouts/readthedocs.org/user_builds/homeassistantapi/envs/129/lib/python3.10/site-packages/sphinx/config.py", line 350, in eval_config_file
    exec(code, namespace)
  File "/home/docs/checkouts/readthedocs.org/user_builds/homeassistantapi/checkouts/129/docs/conf.py", line 17, in <module>
    import toml  # type: ignore[import]
ModuleNotFoundError: No module named 'toml'

By adding toml to the poetry dependencies this issue should be resolved.

[GrandMoff100]

MegaLinter status: ✅ SUCCESS

Descriptor	Linter	Files	Fixed	Errors	Elapsed time
✅ ACTION	actionlint	4		0	0.08s
✅ CREDENTIALS	secretlint	yes		no	1.01s
✅ GIT	git_diff	yes		no	0.01s
✅ JSON	eslint-plugin-jsonc	2	0	0	1.04s
✅ JSON	jsonlint	2		0	0.6s
✅ JSON	prettier	2	0	0	0.58s
✅ JSON	v8r	2		0	2.88s
✅ MARKDOWN	markdownlint	5	0	0	0.4s
✅ MARKDOWN	markdown-link-check	5		0	4.39s
✅ MARKDOWN	markdown-table-formatter	5	0	0	0.3s
✅ SPELL	misspell	27	0	0	0.06s
✅ YAML	prettier	8	0	0	0.81s
✅ YAML	v8r	8		0	11.99s
✅ YAML	yamllint	8		0	0.22s

See errors details in artifact MegaLinter reports on CI Job page