don't expose priv key

src/pg.ml

@@ -101,14 +101,7 @@ let activate_signing_key =
   fun (module Conn : CONN)
     ~master_sig
     Signkey_data.
-      {
-        pub;
-        priv= _;
-        stamp_start;
-        stamp_expire;
-        stamp_end;
-        master_sig= master_sig_opt;
-      }
+      { pub; stamp_start; stamp_expire; stamp_end; master_sig= master_sig_opt }
   ->
     assert (master_sig_opt = Some master_sig);
     Conn.exec insert_signkey
@@ -144,7 +137,6 @@ let add_denomination_key =
     Denom_data.
       {
         pub;
-        priv= _;
         section_name= _;
         value;
         stamp_start;