Replace setup.py with pyproject.toml (#16)

* Replace setup.py with pyproject.toml

pyproject.toml is the modern way of listing package metadata.
Since this library is not doing anything complex in the build process the setup.py is no longer needed.

* Fix find packages

Author: gentlegiantJGC

pyproject.toml

@@ -0,0 +1,28 @@
+[build-system]
+requires = ["setuptools"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "pybind11-stubgen"
+description = "PEP 561 type stubs generator for pybind11 modules"
+version = "2.5.5"
+requires-python = "~=3.7"
+authors = [
+    {name = "Sergei Izmailov", email = "sergei.a.izmailov@gmail.com"},
+]
+license = "BSD-3-Clause"
+license-files = ["LICENSE"]
+dynamic = ["readme"]
+
+[project.urls]
+Repository = "https://github.com/sizmailov/pybind11-stubgen"
+Issues = "https://github.com/sizmailov/pybind11-stubgen/issues"
+
+[tool.setuptools.packages]
+find = {}
+
+[tool.setuptools.dynamic]
+readme = {file = ["README.md"], content-type = "text/markdown"}
+
+[project.entry-points.console_scripts]
+pybind11-stubgen = "pybind11_stubgen.__init__:main"