Bump dnspython from 2.2.1 to 2.3.0 (#1975)

* Bump dnspython from 2.2.1 to 2.3.0

Bumps [dnspython](https://github.com/rthalley/dnspython) from 2.2.1 to 2.3.0.
- [Release notes](https://github.com/rthalley/dnspython/releases)
- [Changelog](https://github.com/rthalley/dnspython/blob/master/doc/whatsnew.rst)
- [Commits](https://github.com/rthalley/dnspython/compare/v2.2.1...v2.3.0)

---
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==2.3.0

---------

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

@@ -1,26 +1,33 @@
 # Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
 
+from typing import Dict
+
 import dns.exception
 
 # pylint: disable=unused-import
 
-from dns._asyncbackend import Socket, DatagramSocket, \
-    StreamSocket, Backend  # noqa:
+from dns._asyncbackend import (
+    Socket,
+    DatagramSocket,
+    StreamSocket,
+    Backend,
+)  # noqa: F401  lgtm[py/unused-import]
 
 # pylint: enable=unused-import
 
 _default_backend = None
 
-_backends = {}
+_backends: Dict[str, Backend] = {}
 
 # Allow sniffio import to be disabled for testing purposes
 _no_sniffio = False
 
+
 class AsyncLibraryNotFoundError(dns.exception.DNSException):
     pass
 
 
-def get_backend(name):
+def get_backend(name: str) -> Backend:
     """Get the specified asynchronous backend.
 
     *name*, a ``str``, the name of the backend.  Currently the "trio",
@@ -32,22 +39,25 @@ def get_backend(name):
     backend = _backends.get(name)
     if backend:
         return backend
-    if name == 'trio':
+    if name == "trio":
         import dns._trio_backend
+
         backend = dns._trio_backend.Backend()
-    elif name == 'curio':
+    elif name == "curio":
         import dns._curio_backend
+
         backend = dns._curio_backend.Backend()
-    elif name == 'asyncio':
+    elif name == "asyncio":
         import dns._asyncio_backend
+
         backend = dns._asyncio_backend.Backend()
     else:
-        raise NotImplementedError(f'unimplemented async backend {name}')
+        raise NotImplementedError(f"unimplemented async backend {name}")
     _backends[name] = backend
     return backend
 
 
-def sniff():
+def sniff() -> str:
     """Attempt to determine the in-use asynchronous I/O library by using
     the ``sniffio`` module if it is available.
 
@@ -59,35 +69,32 @@ def sniff():
         if _no_sniffio:
             raise ImportError
         import sniffio
+
         try:
             return sniffio.current_async_library()
         except sniffio.AsyncLibraryNotFoundError:
-            raise AsyncLibraryNotFoundError('sniffio cannot determine ' +
-                                            'async library')
+            raise AsyncLibraryNotFoundError(
+                "sniffio cannot determine " + "async library"
+            )
     except ImportError:
         import asyncio
+
         try:
             asyncio.get_running_loop()
-            return 'asyncio'
+            return "asyncio"
         except RuntimeError:
-            raise AsyncLibraryNotFoundError('no async library detected')
-        except AttributeError:  # pragma: no cover
-            # we have to check current_task on 3.6
-            if not asyncio.Task.current_task():
-                raise AsyncLibraryNotFoundError('no async library detected')
-            return 'asyncio'
+            raise AsyncLibraryNotFoundError("no async library detected")
 
 
-def get_default_backend():
-    """Get the default backend, initializing it if necessary.
-    """
+def get_default_backend() -> Backend:
+    """Get the default backend, initializing it if necessary."""
     if _default_backend:
         return _default_backend
 
     return set_default_backend(sniff())
 
 
-def set_default_backend(name):
+def set_default_backend(name: str) -> Backend:
     """Set the default backend.
 
     It's not normally necessary to call this method, as