Remove API deprecated in 1.6, clean up the legacy deprecations (#3468)

* Remove API deprecated in 1.6, clean up the legacy deprecations

* flake8, unused import
diff --git a/tests/test_x509.py b/tests/test_x509.py
index db26f56..de19d0d 100644
--- a/tests/test_x509.py
+++ b/tests/test_x509.py
@@ -521,7 +521,7 @@
         )
 
         with warnings.catch_warnings():
-            warnings.simplefilter("always", utils.DeprecatedIn10)
+            warnings.simplefilter("always", utils.PersistentlyDeprecated)
             assert cert.serial == 2
             assert cert.serial_number == 2
 
@@ -533,7 +533,7 @@
         )
 
         with warnings.catch_warnings():
-            warnings.simplefilter("always", utils.DeprecatedIn10)
+            warnings.simplefilter("always", utils.PersistentlyDeprecated)
             with pytest.deprecated_call():
                 cert.serial
 
diff --git a/tests/test_x509_ext.py b/tests/test_x509_ext.py
index 7104121..8210b05 100644
--- a/tests/test_x509_ext.py
+++ b/tests/test_x509_ext.py
@@ -3003,17 +3003,6 @@
         with pytest.raises(ValueError):
             x509.DistributionPoint("data", "notname", None, None)
 
-    def test_relative_name_name_value_deprecated(self):
-        with pytest.deprecated_call():
-            x509.DistributionPoint(
-                None,
-                x509.Name([
-                    x509.NameAttribute(NameOID.COMMON_NAME, u"myCN")
-                ]),
-                None,
-                None
-            )
-
     def test_crl_issuer_not_general_names(self):
         with pytest.raises(TypeError):
             x509.DistributionPoint(None, None, None, ["notgn"])