Update mdbook to 0.4.45

Changelog: https://github.com/rust-lang/mdBook/blob/master/CHANGELOG.md#mdbook-0445

Author: ehuss

src/tools/rustbook/Cargo.lock

@@ -867,9 +867,9 @@ dependencies = [
 
 [[package]]
 name = "mdbook"
-version = "0.4.44"
+version = "0.4.45"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f9da1e54401fe5d45a664c57e112e70f18e8c5a73e268c179305b932ee864574"
+checksum = "b07d36d96ffe1b5b16ddf2bc80b3b26bb7a498b2a6591061250bf0af8e8095ad"
 dependencies = [
  "ammonia",
  "anyhow",

src/tools/rustbook/Cargo.toml

@@ -14,6 +14,6 @@ mdbook-i18n-helpers = "0.3.3"
 mdbook-spec = { path = "../../doc/reference/mdbook-spec" }
 
 [dependencies.mdbook]
-version = "0.4.44"
+version = "0.4.45"
 default-features = false
 features = ["search"]