add pyproject.toml based on setuptools

pyproject.toml

+[build-system]
+requires = ["setuptools"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "orekitdata"
+version = "0.1.0"
+authors = [
+    {name = "Clément Jonglez", email = "clement.jonglez@tu-berlin.de"},
+]
+description = "Orekit data repository, updated every few months"
+readme = "README.md"
+dependencies = [
+]
+
+[tool.setuptools]
+package-dir = {"orekitdata" = "."}
+
+[tool.setuptools.package-data]
+"*" = ["**"]