treewide: cleanup paramiko.optional-dependency.ed25519

pkgs/development/python-modules/docker/default.nix

···
   ];
 
   optional-dependencies = {
-    ssh = [ paramiko paramiko.optional-dependencies.ed25519 ];
+    ssh = [ paramiko ];
     tls = [];
     websockets = [ websocket-client ];
   };

pkgs/development/python-modules/ncclient/default.nix

···
     paramiko
     lxml
     six
-  ] ++ paramiko.optional-dependencies.ed25519;
+  ];
 
   nativeCheckInputs = [ pytestCheckHook ];
 

pkgs/development/python-modules/sshtunnel/default.nix

···
 
   build-system = [ setuptools ];
 
-  dependencies = [ paramiko ] ++ paramiko.optional-dependencies.ed25519;
+  dependencies = [ paramiko ];
 
   nativeCheckInputs = [
     pytestCheckHook