Add initial Dockerfile for GEOS

.ci/geos_images/Dockerfile

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+FROM debian:bullseye AS builder
+
+RUN apt-get update \
+  && apt-get install -y cmake build-essential wget \
+  && rm -rf /var/lib/apt/lists/*
+
+ARG GEOS_VERSION=3.11.2
+WORKDIR /tmp
+RUN wget https://download.osgeo.org/geos/geos-$GEOS_VERSION.tar.bz2 && \
+	tar -xf geos-$GEOS_VERSION.tar.bz2 && \
+	rm geos-$GEOS_VERSION.tar.bz2
+
+WORKDIR /tmp/geos-$GEOS_VERSION
+RUN cmake . -DCMAKE_INSTALL_PREFIX=/usr/local && \
+    make -j4 && \
+    make install
+
+FROM debian:bullseye
+COPY --from=builder /usr/local/ /usr/local/
+CMD ["geos-config", "--version"]

.ci/geos_images/README.md

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+# GEOS Images
+
+This directory contains a Dockerfile and instructions for how to create GEOS
+images. These images are used for CI.
+
+The images install GEOS from source. This is so that each version of GEOS can
+be used in CI.
+
+## Building and uploading
+
+The following command assume the current working directory is the same as this
+README.
+
+```sh
+docker build .
+```