ci: check for minimal versions with tokio_unstable (#4224)

.github/workflows/ci.yml

@@ -248,6 +248,16 @@ jobs:
           # Update Cargo.lock to minimal version dependencies.
           cargo update -Z minimal-versions
           cargo hack check --all-features --ignore-private
+      - name: "check --all-features --unstable -Z minimal-versions"
+        env:
+          RUSTFLAGS: --cfg tokio_unstable -Dwarnings
+        run: |
+          # Remove dev-dependencies from Cargo.toml to prevent the next `cargo update`
+          # from determining minimal versions based on dev-dependencies.
+          cargo hack --remove-dev-deps --workspace
+          # Update Cargo.lock to minimal version dependencies.
+          cargo update -Z minimal-versions
+          cargo hack check --all-features --ignore-private
 
   fmt:
     name: fmt

tokio/Cargo.toml

@@ -102,7 +102,7 @@ parking_lot = { version = "0.11.0", optional = true }
 # Currently unstable. The API exposed by these features may be broken at any time.
 # Requires `--cfg tokio_unstable` to enable.
 [target.'cfg(tokio_unstable)'.dependencies]
-tracing = { version = "0.1.21", default-features = false, features = ["std"], optional = true } # Not in full
+tracing = { version = "0.1.25", default-features = false, features = ["std"], optional = true } # Not in full
 
 [target.'cfg(unix)'.dependencies]
 libc = { version = "0.2.42", optional = true }