Update to 0.4.21

CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## mdBook 0.4.21
+[92afe9b...8f01d02](https://github.com/rust-lang/mdBook/compare/92afe9b...8f01d02)
+
+### Fixed
+- Fixed an issue where mdBook would fail to compile with Rust nightly-2022-07-22.
+  [#1861](https://github.com/rust-lang/mdBook/pull/1861)
+
 ## mdBook 0.4.20
 [53055e0...da166e0](https://github.com/rust-lang/mdBook/compare/53055e0...da166e0)
 

Cargo.lock

@@ -796,7 +796,7 @@ checksum = "a3e378b66a060d48947b590737b30a1be76706c8dd7b8ba0f2fe3989c68a853f"
 
 [[package]]
 name = "mdbook"
-version = "0.4.20"
+version = "0.4.21"
 dependencies = [
  "ammonia",
  "anyhow",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "mdbook"
-version = "0.4.20"
+version = "0.4.21"
 authors = [
     "Mathieu David <mathieudavid@mathieudavid.org>",
     "Michael-F-Bryan <michaelfbryan@gmail.com>",

guide/src/continuous-integration.md

@@ -21,7 +21,7 @@ A simple approach would be to use the popular `curl` CLI tool to download the ex
 
 ```sh
 mkdir bin
-curl -sSL https://github.com/rust-lang/mdBook/releases/download/v0.4.20/mdbook-v0.4.20-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=bin
+curl -sSL https://github.com/rust-lang/mdBook/releases/download/v0.4.21/mdbook-v0.4.21-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=bin
 bin/mdbook build
 ```