Improve readability of incremental install simulator

pysr/test/incremental_install_simulator.dockerfile

@@ -3,15 +3,15 @@ FROM debian:bullseye-slim
 ENV DEBIAN_FRONTEND=noninteractive
 
 # Install juliaup and pyenv:
-RUN apt-get update && apt-get install -y curl
+RUN apt-get update && apt-get install -y curl git build-essential \
+    libssl-dev zlib1g-dev libbz2-dev libreadline-dev libsqlite3-dev \
+    libncurses5-dev libncursesw5-dev xz-utils libffi-dev liblzma-dev && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/*
 
 # Install juliaup:
 RUN curl -fsSL https://install.julialang.org | sh -s -- -y
 
-RUN apt-get install -y git build-essential libssl-dev zlib1g-dev libbz2-dev \
-    libreadline-dev libsqlite3-dev libncurses5-dev libncursesw5-dev \
-    xz-utils libffi-dev liblzma-dev
-
 # Install pyenv:
 RUN curl -fsSL curl https://pyenv.run | sh && \
     echo 'export PATH="/root/.pyenv/bin:$PATH"' >> ~/.bashrc && \
@@ -26,22 +26,23 @@ RUN juliaup add 1.8 && juliaup default 1.8
 RUN pyenv install 3.9.2 && pyenv global 3.9.2
 RUN python3 -m pip install --upgrade pip
 
-# Try to install pysr:
+# Get PySR source:
 WORKDIR /pysr
 ADD ./requirements.txt /pysr/requirements.txt
 RUN python3 -m pip install -r /pysr/requirements.txt
 
 ADD ./setup.py /pysr/setup.py
 ADD ./pysr/ /pysr/pysr/
-RUN python3 -m pip install .
 
+# First install of PySR:
+RUN python3 -m pip install .
 RUN python3 -m pysr install
 
 # Change Python version:
 RUN pyenv install 3.10 && pyenv global 3.10 && pyenv uninstall -f 3.9.2
 RUN python3 -m pip install --upgrade pip
 
-# Try to use PySR:
+# Second install of PySR:
 RUN python3 -m pip install .
 RUN rm -r ~/.julia/environments/pysr-0.14.2
 RUN python3 -m pysr install