add: dart sass installation in Dockerfile

docker/Dockerfile

@@ -3,6 +3,8 @@ FROM nginx:stable
 ARG HUGO_VERSION
 ENV HUGO_VERSION=${HUGO_VERSION}
 ENV HUGO_DEST=/usr/share/nginx/html
+ENV DART_SASS_VERSION=1.105.1
+ENV PATH="/opt/dart-sass:${PATH}"
 
 # Install dependencies
 RUN apt-get update && apt-get install -y \
@@ -15,6 +17,10 @@ RUN apt-get update && apt-get install -y \
 RUN curl -sSL https://github.com/gohugoio/hugo/releases/download/v${HUGO_VERSION}/hugo_extended_${HUGO_VERSION}_Linux-64bit.tar.gz \
     | tar -xz -C /usr/local/bin hugo
 
+# Download Dart Sass
+RUN curl -fsSL https://github.com/sass/dart-sass/releases/download/${DART_SASS_VERSION}/dart-sass-${DART_SASS_VERSION}-linux-x64.tar.gz \
+    | tar -xz -C /opt
+
 # Add entrypoint script
 COPY entrypoint.sh /entrypoint.sh
 RUN chmod +x /entrypoint.sh