catch exceptions as const

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ia8f2ae95679f98f2fc3f32239bbf3b3578c35888
diff --git a/targeting.cpp b/targeting.cpp
index 7b919be..e568bcd 100644
--- a/targeting.cpp
+++ b/targeting.cpp
@@ -92,7 +92,7 @@
             }
         }
     }
-    catch (std::filesystem::filesystem_error& e)
+    catch (const std::filesystem::filesystem_error& e)
     {
         using metadata = xyz::openbmc_project::Common::File::Open;