pw_software_update: Disable spurious Pylint error

Followup to
https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/70301.
Removes another spurious pylint error.

Bug: 572
Change-Id: I44b8fad86baca384319740a352a0e0f75446a628
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/70840
Reviewed-by: Wyatt Hepler <hepler@google.com>
Commit-Queue: Ted Pudlik <tpudlik@google.com>
diff --git a/pw_software_update/py/pw_software_update/keys.py b/pw_software_update/py/pw_software_update/keys.py
index 2a290d1..c9a72d3 100644
--- a/pw_software_update/py/pw_software_update/keys.py
+++ b/pw_software_update/py/pw_software_update/keys.py
@@ -88,9 +88,11 @@
             f'Not an elliptic curve public key type: {type(ec_key)}.'
             'Try generate a key with gen_ecdsa_keypair()?')
 
+    # pylint: disable=no-member
     if not (ec_key.curve.name == 'secp256r1' and ec_key.key_size == 256):
-        raise TypeError(f'Unsupported curve: {ec_key.curve.name}.'  # pylint: disable=no-member
+        raise TypeError(f'Unsupported curve: {ec_key.curve.name}.'
                         'Try generate a key with gen_ecdsa_keypair()?')
+    # pylint: enable=no-member
 
     tuf_key = Key(key_type=KeyType.ECDSA_SHA2_NISTP256,
                   scheme=KeyScheme.ECDSA_SHA2_NISTP256_SCHEME,