ci: try to download the mdbook-admonish binary instead

.github/workflows/book.yml

@@ -15,11 +15,20 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: stable
-      - run: (test -x $HOME/.cargo/bin/mdbook || cargo install --vers "^0.4" mdbook)
-      - run: cargo install --vers "^1.17" mdbook-admonish
+      - name: Install latest mdbook
+        run: |
+          tag=$(curl 'https://api.github.com/repos/rust-lang/mdbook/releases/latest' | jq -r '.tag_name')
+          url="https://github.com/rust-lang/mdbook/releases/download/${tag}/mdbook-${tag}-x86_64-unknown-linux-gnu.tar.gz"
+          mkdir mdbook
+          curl -sSL $url | tar -xz --directory=./mdbook
+          echo `pwd`/mdbook >> $GITHUB_PATH
+      - name: Install latest mdbook-admonish
+        run: |
+          tag=$(curl 'https://api.github.com/repos/tommilligan/mdbook-admonish/releases/latest' | jq -r '.tag_name')
+          url="https://github.com/tommilligan/mdbook-admonish/releases/download/${tag}/mdbook-admonish-${tag}-x86_64-unknown-linux-gnu.tar.gz"
+          mkdir mdbook-admonish
+          curl -sSL $url | tar -xz --directory=./mdbook-admonish
+          echo `pwd`/mdbook-admonish >> $GITHUB_PATH
       - name: Build Book
         run: |
           mdbook build