use attrs directly

src/allmydata/cli/grid_manager.py

@@ -9,6 +9,7 @@ from datetime import (
 )
 
 import click
+import attr
 
 from twisted.python.filepath import (
     FilePath,
@@ -196,7 +197,7 @@ def sign(ctx, name, expiry_days):
             "No storage-server called '{}' exists".format(name)
         )
 
-    certificate_data = json.dumps(certificate.asdict(), indent=4)
+    certificate_data = json.dumps(attr.asdict(certificate), indent=4)
     click.echo(certificate_data)
     if fp is not None:
         next_serial = 0

src/allmydata/grid_manager.py

@@ -19,7 +19,10 @@ from allmydata.util import (
     dictutil,
 )
 
-from attrs import define, asdict, Factory
+from attrs import (
+    define,
+    Factory,
+)
 
 
 @define
@@ -41,9 +44,6 @@ class SignedCertificate(object):
             signature=data["signature"].encode("ascii")
         )
 
-    def asdict(self):
-        return asdict(self)
-
 
 @define
 class _GridManagerStorageServer(object):