Build wheels in Ubuntu 16.04 Docker image, since ones built in 14.04 …

…segfault on 21.04 (#2)

Dockerfile

@@ -1,8 +1,8 @@
-FROM ubuntu:14.04
+FROM ubuntu:16.04
 
 RUN apt-get update && apt-get install -y curl git build-essential \
   libssl-dev zlib1g-dev libncurses5-dev libncursesw5-dev libreadline-dev libsqlite3-dev \
-  libgdbm-dev libdb5.3-dev libbz2-dev libexpat1-dev liblzma-dev libffi-dev uuid-dev \
+  libgdbm-dev libdb5.3-dev libbz2-dev libexpat1-dev liblzma-dev libffi-dev libssl-dev uuid-dev \
   python python3 python-dev python3-dev
 
 RUN curl -L https://github.com/pyenv/pyenv-installer/raw/master/bin/pyenv-installer | bash
@@ -13,20 +13,6 @@ ENV PATH $PYENV_ROOT/shims:$PYENV_ROOT/bin:$PATH
 RUN pyenv install 3.4.10
 RUN pyenv install 3.5.7
 RUN pyenv install 3.6.9
-
-# Python 3.7 requires ssl >= 1.1 but Ubuntu 14.04 only provides 1.0.1.
-# Build openssl 1.1 and install in homedir.
-RUN curl -LO https://www.openssl.org/source/openssl-1.1.1b.tar.gz
-RUN tar zxvf openssl-1.1.1b.tar.gz
-WORKDIR openssl-1.1.1b
-RUN ./config --prefix=$HOME/openssl --openssldir=$HOME/openssl
-RUN make install
-ENV CFLAGS=-I$HOME/openssl/include
-ENV LDFLAGS=-L$HOME/openssl/lib
-ENV LD_LIBRARY_PATH=$HOME/openssl/lib:$LD_LIBRARY_PATH
-ENV SSH=$HOME/openssl
-WORKDIR /
-
 RUN pyenv install 3.7.4
 RUN pyenv install 3.8.2
 RUN pyenv install 3.9.6