Allow building with boost 1.87

Boost for whatever reason added nodiscard on boost::asio::spawn.  Long
term someone likely needs to move this coroutine stuff over to c++20
coroutines, but for now, put in maybe_unused where appropriate.

Change-Id: I72c2039a2bb1e6198a543f89a1820ed3cb78c9df
Signed-off-by: Ed Tanous <ed@tanous.net>
diff --git a/dbus-sdr/storagecommands.cpp b/dbus-sdr/storagecommands.cpp
index d169367..3d16344 100644
--- a/dbus-sdr/storagecommands.cpp
+++ b/dbus-sdr/storagecommands.cpp
@@ -20,6 +20,7 @@
 #include "selutility.hpp"
 
 #include <boost/algorithm/string.hpp>
+#include <boost/asio/detached.hpp>
 #include <boost/container/flat_map.hpp>
 #include <boost/process.hpp>
 #include <ipmid/api.hpp>
@@ -346,11 +347,12 @@
         });
 
     // call once to populate
-    (void)boost::asio::spawn(*getIoContext(),
-                             [](boost::asio::yield_context yield) {
-                                 replaceCacheFru(getSdBus(), yield);
-                             },
-                             {});
+    boost::asio::spawn(
+        *getIoContext(),
+        [](boost::asio::yield_context yield) {
+            replaceCacheFru(getSdBus(), yield);
+        },
+        boost::asio::detached);
 }
 
 /** @brief implements the read FRU data command