bpo-34001: add test for protocol boundary restrictions

This commit adds tests for the new {min,max}imum_version restrictions.
Attempting to set an invalid range should ValueError, and the value
should not be changed after the attempt.

Lib/test/test_ssl.py

@@ -1105,6 +1105,23 @@ def test_min_max_version(self):
             {ssl.TLSVersion.TLSv1_2, ssl.TLSVersion.TLSv1_3}
         )
 
+        with self.assertRaises(ValueError):
+            ctx.maximum_version = ssl.TLSVersion.MINIMUM_SUPPORTED
+
+        self.assertEqual(
+            ctx.maximum_version, ssl.TLSVersion.MAXIMUM_SUPPORTED
+        )
+
+        ctx.minimum_version = ssl.TLSVersion.MINIMUM_SUPPORTED
+        ctx.maximum_version = ssl.TLSVersion.MINIMUM_SUPPORTED
+
+        with self.assertRaises(ValueError):
+            ctx.minimum_version = ssl.TLSVersion.MAXIMUM_SUPPORTED
+
+        self.assertEqual(
+            ctx.minimum_version, ssl.TLSVersion.MINIMUM_SUPPORTED
+        )
+
         with self.assertRaises(ValueError):
             ctx.minimum_version = 42