Update buffa deps to 0.6.0

Author: pkwarren

plugins/anthropics/connect-rust/v0.5.0/buf.plugin.yaml

@@ -22,15 +22,15 @@ registry:
       # buffa::bytes::Bytes directly. Message types live in the buffa SDK
       # crate (via the plugin dep above); this dep is for the runtime API.
       - name: "buffa"
-        req: "0.5.2"
+        req: "0.6.0"
         default_features: true
       # Well-known types. Service stubs whose request/response types are
       # WKTs (e.g. google.longrunning.Operations) reference them as
       # `::buffa_types::google::protobuf::...`, mirroring buffa-codegen's
       # extern_path mapping for `.google.protobuf`. Must be a direct dep
       # so the `::buffa_types` path resolves in the generated crate.
       - name: "buffa-types"
-        req: "0.5.2"
+        req: "0.6.0"
         default_features: true
         features:
           - json