guarantee serde is in lockstep with serde_derive

test_suite/assert_lockstep/dummy_dependant/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "dummy_dependant"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+serde = { path = "../../../serde" }
+
+# `workspace.exclude` does not seem to work with doubly nested paths.
+[workspace]

test_suite/assert_lockstep/dummy_dependant/src/lib.rs

@@ -0,0 +1 @@
+