build: pyproject.toml requires-python ~=2.7 or ~= 3.5; restore author; restore description for Py2&3

Author: chaimleib

pyproject.toml

@@ -1,12 +1,13 @@
 [project]
 name = "intervaltree"
-description='Editable interval tree data structure'
+description='Editable interval tree data structure for Python 2 and 3'
 version = "3.2.0"
 authors = [
   { name="Chaim Leib Halbert", email="[email protected]" },
+  { name="Konstantin Tretyakov" },
 ]
 readme = "README.md"
-requires-python = ">=3.6"
+requires-python = ">= 2.7.18, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*"
 classifiers = [
         'Development Status :: 5 - Production/Stable',
         'Programming Language :: Python :: Implementation :: PyPy',