remove now stable doctest-xcompile (#3893)

Author: Madoshakalaka

.cargo/config.toml

@@ -3,8 +3,3 @@ runner = 'wasm-bindgen-test-runner'
 
 [target.'cfg(all(target_arch = "wasm32", target_os = "wasi"))']
 runner = 'wasmtime -W unknown-imports-trap=y'
-
-# This section needs to be last.
-# GitHub Actions modifies this section.
-[unstable]
-doctest-xcompile = true

.github/workflows/fmt.yml

@@ -22,4 +22,4 @@ jobs:
           components: rustfmt
 
       - name: Run fmt
-        run: cargo +nightly fmt --all -- --check --unstable-features
+        run: cargo +nightly fmt --all -- --check