Add sudo group to runner

Signed-off-by: Christian Richter <crichter@suse.com>

ghrunner/Dockerfile

@@ -6,8 +6,10 @@ RUN apt-get update \
     && apt-get -y install \
     curl \
     libdigest-sha-perl \
-    tzdata
+    tzdata \
+    sudo
 RUN useradd -ms /bin/bash runner
+RUN usermod -aG sudo runner
 WORKDIR /runner
 RUN chown runner:runner /runner -Rfv
 ENTRYPOINT ["/entrypoint.sh"]