CI: Additional fix for appimage

Additional fix to #31.

Fix this error:
https://github.com/vim-jp/vimdoc-en/actions/runs/3548225724/jobs/5959199695

Author: k-takata

.github/workflows/generate.yml

@@ -13,8 +13,9 @@ jobs:
       - name: Initialization
         run: |
           sudo apt-get update
-          # libfuse2 is needed for appimage.
+          # libfuse2 and LD_PRELOAD are needed for appimage.
           sudo apt-get -y install libfuse2
+          echo "LD_PRELOAD=/lib/x86_64-linux-gnu/libgmodule-2.0.so" >> $GITHUB_ENV
       - name: checkout master
         uses: actions/checkout@v2
         with: