Remove duplicate Python version declarations

ruff can automatically detect this [1] now that it is defined in
pyproject.toml. mypy defaults to the version of Python used to run mypy
[2][3] so we need to keep its configuration around a while longer.

We also fix the 'project.authors' definition while we're here.

[1] https://docs.astral.sh/ruff/settings/#target-version
[2] https://mypy.readthedocs.io/en/stable/config_file.html#confval-python_version
[3] https://github.com/python/mypy/issues/19349

Change-Id: I1feaa80c2e11bce951ae0ab99c6f1f4b00faadb8
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

pyproject.toml

@@ -6,8 +6,7 @@ build-backend = "pbr.build"
 name = "openstacksdk"
 description = "An SDK for building applications to work with OpenStack"
 authors = [
-    {name = "OpenStack"},
-    {email="openstack-discuss@lists.openstack.org"}
+    {name = "OpenStack", email = "openstack-discuss@lists.openstack.org"},
 ]
 readme = {file = "README.rst", content-type = "text/x-rst"}
 license = {text = "Apache-2.0"}
@@ -105,7 +104,6 @@ ignore_errors = true
 
 [tool.ruff]
 line-length = 79
-target-version = "py310"
 
 [tool.ruff.format]
 quote-style = "preserve"