Drop support for unsupported Python versions

tools/python_version_checker.py

@@ -0,0 +1,36 @@
+# SPDX-FileCopyrightText: 2021 Espressif Systems (Shanghai) CO LTD
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# Script for checking the compatibility of the Python interpreter with ESP-IDF.
+#
+# There are related tools/detect_python.{sh,fish} scripts which are called earlier when the paths are not properly
+# set-up and they only intend to prefer the use of Python 3 over Python 2. Why not more? All possible executables
+# (python3.6, python3.7, ...) cannot be hardcoded there and at the end, the user is responsible to set-up a system
+# where "python" or "python3" of compatible version is available.
+
+import sys
+
+try:
+    # Python 2 is not supported anymore but still the old way of typing is used here in order to give a nice Python
+    # version failure and not a typing exception.
+    from typing import Iterable
+except ImportError:
+    pass
+
+OLDEST_PYTHON_SUPPORTED = (3, 6)  # keep it as tuple for comparison with sys.version_info
+
+
+def _ver_to_str(it):  # type: (Iterable) -> str
+    return '.'.join(str(x) for x in it)
+
+
+def is_supported():  # type: () -> bool
+    return sys.version_info[:2] >= OLDEST_PYTHON_SUPPORTED[:2]
+
+
+def check():  # type: () -> None
+    if not is_supported():
+        raise RuntimeError('ESP-IDF supports Python {} or newer but you are using Python {}. Please upgrade your '
+                           'installation as described in the documentation.'.format(_ver_to_str(OLDEST_PYTHON_SUPPORTED),
+                                                                                    _ver_to_str(sys.version_info[:3])))