Don't use deprecated methods in resolve_with()

resolve_with(), which is not deprecated, was using the
deprecated is_valid() method.  Replaced with a lazily instantiated
validator object.

Author: handrews

src/rfc3986/_mixin.py

@@ -56,6 +56,15 @@ def authority_info(self):
     def _match_subauthority(self):
         return misc.SUBAUTHORITY_MATCHER.match(self.authority)
 
+    def _get_base_uri_validator(self):
+        try:
+            return self._base_uri_validator
+        except AttributeError:
+            self._base_uri_validator = (
+                validators.Validator().require_presence_of("scheme")
+            )
+            return self._base_uri_validator
+
     @property
     def host(self):
         """If present, a string representing the host."""
@@ -262,7 +271,9 @@ def resolve_with(self, base_uri, strict=False):
         if not isinstance(base_uri, URIMixin):
             base_uri = type(self).from_string(base_uri)
 
-        if not base_uri.is_valid(require_scheme=True):
+        try:
+            self._get_base_uri_validator().validate(base_uri)
+        except exc.ValidationError:
             raise exc.ResolutionError(base_uri)
 
         # This is optional per