update images to versions supported by pi-hole 5

Signed-off-by: pvogt09 <50047961+pvogt09@users.noreply.github.com>

test/ubuntu_20.Dockerfile

@@ -0,0 +1,16 @@
+FROM buildpack-deps:focal-scm
+
+ENV GITDIR /etc/.pihole
+ENV SCRIPTDIR /opt/pihole
+
+RUN mkdir -p $GITDIR $SCRIPTDIR /etc/pihole
+ADD . $GITDIR
+RUN cp $GITDIR/advanced/Scripts/*.sh $GITDIR/gravity.sh $GITDIR/pihole $GITDIR/automated\ install/*.sh $SCRIPTDIR/
+ENV PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:$SCRIPTDIR
+
+RUN true && \
+    chmod +x $SCRIPTDIR/*
+
+ENV PH_TEST true
+
+#sed '/# Start the installer/Q' /opt/pihole/basic-install.sh > /opt/pihole/stub_basic-install.sh && \