message: Upgrade mdbook to 0.3
diff: @@ -26,12 +26,12 @@ jobs:
  ~/.cargo/bin
  ~/.cargo/registry/index
  ~/.cargo/registry/cache
  - key: ${{ runner.os }}-build-${{ env.cache-name }}-0.2 }}
  + key: ${{ runner.os }}-build-${{ env.cache-name }}-0.3 }}
  - name: Install mdbook
  run: |
  (test -x $HOME/.cargo/bin/cargo-install-update || cargo install cargo-update)
  - (test -x $HOME/.cargo/bin/mdbook || cargo install --vers "^0.2" mdbook)
  + (test -x $HOME/.cargo/bin/mdbook || cargo install --vers "^0.3" mdbook)
  cargo install-update -a
  - name: Build book
  