Auto merge of #11716 - weihanglo:bump-mdbook, r=Muscraft

chore: bump mdbook to 0.4.27

Previously mdbook was bumped in #11646 for contrib.yml worflow
but main.yaml workflow. This makes the two in sync and also
upgrades to the latest 0.4.27. (Though there is nothing really
changed for application users as us)

Author: bors

.github/workflows/contrib.yml

@@ -19,7 +19,7 @@ jobs:
     - name: Install mdbook
       run: |
         mkdir mdbook
-        curl -Lf https://github.com/rust-lang/mdBook/releases/download/v0.4.26/mdbook-v0.4.26-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=./mdbook
+        curl -Lf https://github.com/rust-lang/mdBook/releases/download/v0.4.27/mdbook-v0.4.27-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=./mdbook
         echo `pwd`/mdbook >> $GITHUB_PATH
     - name: Deploy docs
       run: |

.github/workflows/main.yml

@@ -170,7 +170,7 @@ jobs:
     - run: cd src/doc/semver-check && cargo +stable run
     - run: |
         mkdir mdbook
-        curl -Lf https://github.com/rust-lang/mdBook/releases/download/v0.4.5/mdbook-v0.4.5-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=./mdbook
+        curl -Lf https://github.com/rust-lang/mdBook/releases/download/v0.4.27/mdbook-v0.4.27-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=./mdbook
         echo `pwd`/mdbook >> $GITHUB_PATH
     - run: cargo doc --document-private-items --no-deps
       env: