No untyped defs in register_new_matrix_user

This one might be contraversial. `request_registration` has three
dependency-injection arguments used for testing. I'm removing the
injection of the `requests` module and using `unitest.mock.patch` in the
test cases instead.

Doing `reveal_type(requests)` and `reveal_type(requests.get)` before the
change:

```
synapse/_scripts/register_new_matrix_user.py:45: note: Revealed type is "Any"
synapse/_scripts/register_new_matrix_user.py:46: note: Revealed type is "Any"
```

And after:

```
synapse/_scripts/register_new_matrix_user.py:44: note: Revealed type is "types.ModuleType"
synapse/_scripts/register_new_matrix_user.py:45: note: Revealed type is "def (url: Union[builtins.str, builtins.bytes], params: Union[Union[_typeshed.SupportsItems[Union[builtins.str, builtins.bytes, builtins.int, builtins.float], Union[builtins.str, builtins.bytes, builtins.int, builtins.float, typing.Iterable[Union[builtins.str, builtins.bytes, builtins.int, builtins.float]], None]], Tuple[Union[builtins.str, builtins.bytes, builtins.int, builtins.float], Union[builtins.str, builtins.bytes, builtins.int, builtins.float, typing.Iterable[Union[builtins.str, builtins.bytes, builtins.int, builtins.float]], None]], typing.Iterable[Tuple[Union[builtins.str, builtins.bytes, builtins.int, builtins.float], Union[builtins.str, builtins.bytes, builtins.int, builtins.float, typing.Iterable[Union[builtins.str, builtins.bytes, builtins.int, builtins.float]], None]]], builtins.str, builtins.bytes], None] =, data: Union[Any, None] =, headers: Union[Any, None] =, cookies: Union[Any, None] =, files: Union[Any, None] =, auth: Union[Any, None] =, timeout: Union[Any, None] =, allow_redirects: builtins.bool =, proxies: Union[Any, None] =, hooks: Union[Any, None] =, stream: Union[Any, None] =, verify: Union[Any, None] =, cert: Union[Any, None] =, json: Union[Any, None] =) -> requests.models.Response"
```

synapse/_scripts/register_new_matrix_user.py

@@ -22,7 +22,7 @@
 import sys
 from typing import Callable, Optional
 
-import requests as _requests
+import requests
 import yaml
 
 
@@ -33,7 +33,6 @@ def request_registration(
     shared_secret: str,
     admin: bool = False,
     user_type: Optional[str] = None,
-    requests=_requests,
     _print: Callable[[str], None] = print,
     exit: Callable[[int], None] = sys.exit,
 ) -> None:

tests/scripts/test_new_matrix_user.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from unittest.mock import Mock
+from unittest.mock import Mock, patch
 
 from synapse._scripts.register_new_matrix_user import request_registration
 
@@ -52,16 +52,16 @@ def post(url, json=None, verify=None):
         out = []
         err_code = []
 
-        request_registration(
-            "user",
-            "pass",
-            "matrix.org",
-            "shared",
-            admin=False,
-            requests=requests,
-            _print=out.append,
-            exit=err_code.append,
-        )
+        with patch("synapse._scripts.register_new_matrix_user.requests", requests):
+            request_registration(
+                "user",
+                "pass",
+                "matrix.org",
+                "shared",
+                admin=False,
+                _print=out.append,
+                exit=err_code.append,
+            )
 
         # We should get the success message making sure everything is OK.
         self.assertIn("Success!", out)
@@ -88,16 +88,16 @@ def get(url, verify=None):
         out = []
         err_code = []
 
-        request_registration(
-            "user",
-            "pass",
-            "matrix.org",
-            "shared",
-            admin=False,
-            requests=requests,
-            _print=out.append,
-            exit=err_code.append,
-        )
+        with patch("synapse._scripts.register_new_matrix_user.requests", requests):
+            request_registration(
+                "user",
+                "pass",
+                "matrix.org",
+                "shared",
+                admin=False,
+                _print=out.append,
+                exit=err_code.append,
+            )
 
         # Exit was called
         self.assertEqual(err_code, [1])
@@ -140,16 +140,16 @@ def post(url, json=None, verify=None):
         out = []
         err_code = []
 
-        request_registration(
-            "user",
-            "pass",
-            "matrix.org",
-            "shared",
-            admin=False,
-            requests=requests,
-            _print=out.append,
-            exit=err_code.append,
-        )
+        with patch("synapse._scripts.register_new_matrix_user.requests", requests):
+            request_registration(
+                "user",
+                "pass",
+                "matrix.org",
+                "shared",
+                admin=False,
+                _print=out.append,
+                exit=err_code.append,
+            )
 
         # Exit was called
         self.assertEqual(err_code, [1])