Update main.yml

.github/workflows/main.yml

@@ -29,7 +29,6 @@ jobs:
         echo "$(pwd)/bin" >> ${GITHUB_PATH}
     - name: Install mdbook-latex-pdf
       run: |
-        mkdir bin
         curl -sL -o bin/mdbook-latex-pdf https://github.com/KaiserY/mdbook-latex-pdf/releases/download/0.1.0/mdbook-latex-pdf-x86_64-unknown-linux-gnu
         chmod +x bin/mdbook-latex-pdf
         echo "$(pwd)/bin" >> ${GITHUB_PATH}