install mermaid-filter

Author: ma91n

.github/workflows/GHPages.yml

@@ -14,7 +14,8 @@ jobs:
         with:
           args: |
             sh -c "
-              apk add --no-cache nodejs npm \
+              apk update \
+              && apk add --no-cache nodejs npm \
               && npm install -g mermaid-filter \
               && sh build-resources-with-pandoc.sh
             "