Fix CA certificates after change of Let's Encrypt root CA

Change-Id: Ibf9d49f7b5e506df4400b49a1fafbd77c7c0c7b6
diff --git a/jenkins-docker/master/Dockerfile b/jenkins-docker/master/Dockerfile
index 52137d2..da5a1c8 100644
--- a/jenkins-docker/master/Dockerfile
+++ b/jenkins-docker/master/Dockerfile
@@ -9,6 +9,7 @@
 COPY jenkins.sh /usr/local/bin/
 
 RUN apt-get update && apt-get install -y \
+    ca-certificates \
     python-dev \
     python-pip \
     python-yaml \
@@ -22,6 +23,9 @@
     pip install pbr==2.0.0 && \
     mkdir -p /etc/jenkins_jobs && chown jenkins: /etc/jenkins_jobs
 
+RUN sed -i 's#mozilla/DST_Root_CA_X3.crt#!mozilla/DST_Root_CA_X3.crt#' /etc/ca-certificates.conf && \
+    update-ca-certificates
+
 # Install JJB from source until the support for checks-filters is released
 RUN git clone https://review.opendev.org/jjb/jenkins-job-builder && \
     cd jenkins-job-builder && \