Add an exception at install for python < 3.6.2

ChangeLog

@@ -6,6 +6,11 @@ What's New in astroid 2.9.0?
 ============================
 Release date: TBA
 
+* The last version compatible with python '3.6.0' and '3.6.1' is astroid '2.6.6'. We did not
+  realize that when adding incompatible typing at the time, and versions might be broken
+  for this interpreter. 2.9.0 meta-information will permit to download pylint on those
+  interpreters but the installation will fail and tell you to install '2.6.6' instead.
+  astroid 2.9.1 will require python >= 3.6.2.
 
 
 What's New in astroid 2.8.6?

setup.py

@@ -1,3 +1,19 @@
+import sys
+
 from setuptools import setup
 
+
+class AstroidIncompatiblePythonError(Exception):
+    def __init__(self) -> None:
+        super().__init__(
+            "The last version compatible with python '3.6.0' and '3.6.1' is astroid '2.6.6'"
+            f"You're using {'.'.join([str(v) for v in sys.version_info[:3]])}. "
+            "Please install astroid 2.6.6 explicitly or upgrade your python interpreter "
+            "to at least 3.6.2. Remember that Python 3.6 end life is December 2021. "
+            "See https://github.com/PyCQA/pylint/issues/5065 for more detail."
+        )
+
+
+if sys.version_info < (3, 6, 2):
+    raise AstroidIncompatiblePythonError()
 setup()