increase minor version

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

docker/ubuntu-20-04.Dockerfile

@@ -0,0 +1,45 @@
+# -------------
+# OS Base image
+# -------------
+# >> Includes system-wide dependencies
+FROM ubuntu:20.04 as lib-base
+ARG DEBIAN_FRONTEND=noninteractive
+RUN apt-get update && \
+    apt-get -y --no-install-recommends install \
+        cmake \
+        make \
+        clang \
+        g++ \
+        curl \
+        default-jdk \
+        python3 \
+        python3-setuptools \
+        python-is-python3 \
+        sudo
+
+# ----------------
+# Z3 Builder Image
+# ----------------
+# >> Includes build files and compiles the basic z3 sources
+FROM lib-base as builder
+COPY ./ /z3-source/
+WORKDIR /z3-source/
+RUN python scripts/mk_make.py
+WORKDIR /z3-source/build/
+RUN make
+RUN sudo make install
+WORKDIR /z3-source/
+
+# -------
+# Bare z3
+# -------
+# >> Includes only stnadard z3 installations.
+# >> Can be used as a standalone interface to z3.
+FROM builder as bare-z3
+ENTRYPOINT [ "z3" ]
+
+# TODO: introduce Python-binding stage
+# ...
+
+# TODO(optional): introduce C/C++ -binding stage
+# ...