Add generic dockerfile for github runners based on ubuntu

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

ghrunner/Dockerfile

@@ -0,0 +1,14 @@
+FROM ubuntu:latest
+COPY entrypoint.sh /
+ENV TZ=Europe/Berlin
+ENV DEBIAN_FRONTEND=noninteractive
+RUN apt-get update \
+    && apt-get -y install \
+    curl \
+    libdigest-sha-perl \
+    tzdata
+RUN useradd -ms /bin/bash runner
+WORKDIR /runner
+RUN chown runner:runner /runner -Rfv
+ENTRYPOINT ["/entrypoint.sh"]
+