[container] Update Dockerfile for PEP 518 build

Dockerfile

@@ -9,27 +9,28 @@ RUN apt-get update \
         ca-certificates \
         locales \
         python3 \
-        python3-setuptools \
+        python3-pip \
     && localedef \
         -i en_US \
         -c \
         -f UTF-8 \
-        -A /usr/share/locale/locale.alias en_US.UTF-8
+        -A /usr/share/locale/locale.alias \
+        en_US.UTF-8
 
-COPY setup.cfg setup.py *.md /usr/src/app/
+COPY pyproject.toml setup.cfg *.md /usr/src/app/
 COPY doc/*.md /usr/src/app/doc/
 COPY man/asciinema.1 /usr/src/app/man/
 COPY asciinema/ /usr/src/app/asciinema/
+COPY README.md LICENSE /usr/src/app/
 
 WORKDIR /usr/src/app
 
-RUN python3 setup.py install
+RUN pip3 install .
+
+WORKDIR /root
 
 ENV LANG="en_US.utf8"
 ENV SHELL="/bin/bash"
-ENV USER="docker"
-
-WORKDIR /root
 
 ENTRYPOINT ["/usr/local/bin/asciinema"]
 CMD ["--help"]