catch exceptions as const

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Iee4354d96981eac216425c71668f8eb72e146977
diff --git a/snmp_serialize.cpp b/snmp_serialize.cpp
index 2a04109..1b47d4e 100644
--- a/snmp_serialize.cpp
+++ b/snmp_serialize.cpp
@@ -82,7 +82,7 @@
         }
         return false;
     }
-    catch (cereal::Exception& e)
+    catch (const cereal::Exception& e)
     {
         log<level::ERR>(e.what());
         std::error_code ec;