Bump dnspython from 2.0.0 to 2.2.0 (#1618)

* Bump dnspython from 2.0.0 to 2.2.0

Bumps [dnspython]() from 2.0.0 to 2.2.0.

---
updated-dependencies:
- dependency-name: dnspython
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

* Update dnspython==2.2.0

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: JonnyWong16 <9099342+JonnyWong16@users.noreply.github.com>

[skip ci]

lib/dns/immutable.py

@@ -0,0 +1,70 @@
+# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
+
+import collections.abc
+import sys
+
+# pylint: disable=unused-import
+if sys.version_info >= (3, 7):
+    odict = dict
+    from dns._immutable_ctx import immutable
+else:
+    # pragma: no cover
+    from collections import OrderedDict as odict
+    from dns._immutable_attr import immutable  # noqa
+# pylint: enable=unused-import
+
+
+@immutable
+class Dict(collections.abc.Mapping):
+    def __init__(self, dictionary, no_copy=False):
+        """Make an immutable dictionary from the specified dictionary.
+
+        If *no_copy* is `True`, then *dictionary* will be wrapped instead
+        of copied.  Only set this if you are sure there will be no external
+        references to the dictionary.
+        """
+        if no_copy and isinstance(dictionary, odict):
+            self._odict = dictionary
+        else:
+            self._odict = odict(dictionary)
+        self._hash = None
+
+    def __getitem__(self, key):
+        return self._odict.__getitem__(key)
+
+    def __hash__(self):  # pylint: disable=invalid-hash-returned
+        if self._hash is None:
+            h = 0
+            for key in sorted(self._odict.keys()):
+                h ^= hash(key)
+            object.__setattr__(self, '_hash', h)
+        # this does return an int, but pylint doesn't figure that out
+        return self._hash
+
+    def __len__(self):
+        return len(self._odict)
+
+    def __iter__(self):
+        return iter(self._odict)
+
+
+def constify(o):
+    """
+    Convert mutable types to immutable types.
+    """
+    if isinstance(o, bytearray):
+        return bytes(o)
+    if isinstance(o, tuple):
+        try:
+            hash(o)
+            return o
+        except Exception:
+            return tuple(constify(elt) for elt in o)
+    if isinstance(o, list):
+        return tuple(constify(elt) for elt in o)
+    if isinstance(o, dict):
+        cdict = odict()
+        for k, v in o.items():
+            cdict[k] = constify(v)
+        return Dict(cdict, True)
+    return o