mdBook: update to 0.0.28.

Closes: #9867 [via git-merge-pr]

srcpkgs/mdBook/template

@@ -1,6 +1,6 @@
 # Template file for 'mdBook'
 pkgname=mdBook
-version=0.0.27
+version=0.0.28
 revision=1
 hostmakedepends="cargo"
 short_desc="Create book from markdown files. Like Gitbook but implemented in Rust"
@@ -8,13 +8,17 @@ maintainer="Huidong Hwang <hwangh95@gmail.com>"
 license="MPL-2.0"
 homepage="https://github.com/rust-lang-nursery/${pkgname}"
 distfiles="https://github.com/rust-lang-nursery/${pkgname}/archive/${version}.tar.gz"
-checksum=5e79e5cd36e84a4a88948dd0c62b02c58dd698e8d72ee73e317b5b56abaa8ca9
+checksum=3cac914a99967e3db11e0a7cc32d47f814f7fced2ba48066efde0ca2340f69bf
 nocross="This cannot be cross compiled due to limitations in cargo."
 
 do_build() {
 	cargo build --release
 }
 
+do_check() {
+	cargo test --release
+}
+
 do_install() {
 	vbin target/release/mdbook
 	vlicense LICENSE