[XrdSsiPb] Updates submodule

On a failed Send(), the client tries to reestablish the connection to the Server.

xrootd-ssi-protobuf-interface @ 223c2e12

-Subproject commit 64b6a514a5059a0a4d9748578218f4f6a4d95d23
+Subproject commit 223c2e127c6b7530e839c52665e35c45dfd4fb7f