Get rid of push_back in favor of emplace_back

Change-Id: I4a0096441ed725eb21e42eb9cc17a173929e3788
diff --git a/src/yang_schema.cpp b/src/yang_schema.cpp
index 4b65e13..9e63348 100644
--- a/src/yang_schema.cpp
+++ b/src/yang_schema.cpp
@@ -248,7 +248,7 @@
             {
                 auto resUnion = yang::Union{};
                 for (auto unionType : type->info()->uni()->types()) {
-                    resUnion.m_unionTypes.push_back(resolveType(unionType));
+                    resUnion.m_unionTypes.emplace_back(resolveType(unionType));
                 }
                 resType.emplace<yang::Union>(std::move(resUnion));
                 break;