chore: prepare v0.2.4 release (#1917)

Includes a `Mutex` bug fix

tokio/CHANGELOG.md

@@ -1,3 +1,8 @@
+# 0.2.4 (December 6, 2019)
+
+### Fixes
+- `sync::Mutex` deadlock when `lock()` future is dropped early (#1898).
+
 # 0.2.3 (December 6, 2019)
 
 ### Added

tokio/Cargo.toml

@@ -8,12 +8,12 @@ name = "tokio"
 #   - README.md
 # - Update CHANGELOG.md.
 # - Create "v0.2.x" git tag.
-version = "0.2.3"
+version = "0.2.4"
 edition = "2018"
 authors = ["Tokio Contributors <[email protected]>"]
 license = "MIT"
 readme = "README.md"
-documentation = "https://docs.rs/tokio/0.2.3/tokio/"
+documentation = "https://docs.rs/tokio/0.2.4/tokio/"
 repository = "https://github.com/tokio-rs/tokio"
 homepage = "https://tokio.rs"
 description = """

tokio/src/lib.rs

@@ -1,4 +1,4 @@
-#![doc(html_root_url = "https://docs.rs/tokio/0.2.3")]
+#![doc(html_root_url = "https://docs.rs/tokio/0.2.4")]
 #![warn(
     missing_debug_implementations,
     missing_docs,