Avoid DeprecationWarning from urllib3 (#719)

* Avoid DeprecationWarning from urllib3

* Don't use a version check

* Add coverage of deprecated kwarg

* Skip deprecation coverage

twine/repository.py

@@ -77,12 +77,19 @@ def __init__(
 
     @staticmethod
     def _make_adapter_with_retries() -> adapters.HTTPAdapter:
-        retry = urllib3.Retry(
+        retry_kwargs = dict(
             connect=5,
             total=10,
-            method_whitelist=["GET"],
             status_forcelist=[500, 501, 502, 503],
         )
+
+        try:
+            retry = urllib3.Retry(allowed_methods=["GET"], **retry_kwargs)
+        except TypeError:  # pragma: no cover
+            # Avoiding DeprecationWarning starting in urllib3 1.26
+            # Remove when that's the mininum version
+            retry = urllib3.Retry(method_whitelist=["GET"], **retry_kwargs)
+
         return adapters.HTTPAdapter(max_retries=retry)
 
     @staticmethod