add checkout

.github/workflows/pandoc.yml

@@ -14,6 +14,7 @@ jobs:
   convert_via_pandoc:
     runs-on: ubuntu-22.04
     steps:
+      - uses: actions/checkout@v3
       - uses: docker://pandoc/core:2.9
         with:
           args: >-  # allows you to break string into multiple lines