fix: remove unstable config-include hack broken by Rust 1.94

Rust 1.94 stabilized the `include` key in `.cargo/config.toml`.

Author: Madoshakalaka

examples/.cargo/config.toml

@@ -1,7 +1 @@
-# this include is a bit of a hack: due to the unstable nature of the feature,
-# this file only gets included on nightly, hence it can specify "nightly only"
-# rustflags and options
-include = ["unstable.toml", "dummy-min-size-config.toml"]
-
-[unstable]
-config-include = true
+include = ["dummy-min-size-config.toml"]