Tweak dockerfile to install ubuntu's certbot, instead of from the outdated ppa

Dockerfile

@@ -13,12 +13,9 @@ ENV EMAIL=foo@bar.com
 # Comma separated list of domains to acquire certs for
 ENV DOMAINS=foo.com,www.foo.com,bar.foo.com
 
-# Install certbot from PPA instead of ubuntu's repos to ensure we always got the latest
-RUN  echo "deb http://ppa.launchpad.net/certbot/certbot/ubuntu bionic main" > /etc/apt/sources.list.d/letsencrypt.list \
-    && apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 7BF576066ADA65728FC7E70A8C47BE8E75BCA694 \
-    && apt-get update \
-    && apt-get -y --no-install-recommends install certbot \
-    && apt-get clean; rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* /usr/share/doc/*
+RUN apt-get update; \
+  apt-get -y --no-install-recommends install certbot; \
+  apt-get clean; rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* /usr/share/doc/*
 
 # Composer config - add early to benefit from docker build caches
 COPY composer.* /workdir/

release

@@ -1 +1 @@
-3.3.0 3.3 3
+3.3.1 3.3 3