ENH: Update pyproject.toml for ITK 5.4.2

In preparation for release.

Ensure that cmake is 3.16.3 or greater to
match v5.4.2 minimum requirements.

Set minimum python to 3.9

Increment version number.

Author: hjmjohnson

pyproject.toml

@@ -47,7 +47,7 @@ Homepage = "https://github.com/InsightSoftwareConsortium/ITKMeshToPolyData"
 # The versions of CMake to allow. If CMake is not present on the system or does
 # not pass this specifier, it will be downloaded via PyPI if possible. An empty
 # string will disable this check.
-cmake.version = ">=3.16"
+cmake.version = ">=3.16.3"
 
 # A list of args to pass to CMake when configuring the project. Setting this in
 # config or envvar will override toml. See also ``cmake.define``.