Update pyproject data

• set the minimum python version required
• specify projecturl metadata correctly
• handle package version programmatically Closes #15 (closed) and #32 (closed)

pyproject.toml

@@ -9,6 +9,7 @@ license = {file = "LICENSE"}
 classifiers = ["License :: OSI Approved :: MIT License"]
 version = "2023.6.27"
 readme = "README.rst"
+requires-python = ">=3.9"
 dependencies = [
     "archspec",
     "rich",