added tag placeholder [CI SKIP]

Dockerfile

@@ -16,7 +16,7 @@ RUN rm /etc/nginx/sites-enabled/default
 # install ttrss and patch configuration
 WORKDIR /var/www
 RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y curl --no-install-recommends && rm -rf /var/lib/apt/lists/* \
-    && curl -SL https://git.tt-rss.org/git/tt-rss/archive/master.tar.gz | tar xzC /var/www --strip-components 1 \
+    && curl -SL https://git.tt-rss.org/git/tt-rss/archive/<TAG>.tar.gz | tar xzC /var/www --strip-components 1 \
     && apt-get purge -y --auto-remove curl \
     && chown www-data:www-data -R /var/www
 RUN cp config.php-dist config.php