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.

Replace keyword of "ITK" with lowercase "itk"
in some instances to be consistent.

Author: hjmjohnson

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "scikit_build_core.build"
 
 [project]
 name = "itk-fpfh"
-version = "0.2.0"
+version = "0.2.1"
 description = "The feature points could be used obtain salient points while performing registration using RANSAC remote module. The class PointFeature is the main driver that takes a PointSet as argument. Please refer to the documentation for a detailed description and sample usage: https://github.com/InsightSoftwareConsortium/ITKFPFH"
 readme = "README.md"
 license = {file = "LICENSE"}
@@ -33,7 +33,7 @@ classifiers = [
     "Topic :: Scientific/Engineering :: Medical Science Apps.",
     "Topic :: Software Development :: Libraries",
 ]
-requires-python = ">=3.8"
+requires-python = ">=3.9"
 dependencies = [
     "itk == 5.4.*",
 ]