Dockerfile: Split out COPY of pyproject.toml

This way, the `poetry install` gets cached properly and doesn't run
every time.

Signed-off-by: Matthew Cengia <mattcen@mattcen.com>

Dockerfile

@@ -20,8 +20,9 @@ RUN poetry config virtualenvs.in-project true
 
 WORKDIR ${WORKDIR}
 
-COPY --chown=1000:1000 . .
+COPY --chown=1000:1000 pyproject.toml .
 RUN poetry install --only main
+COPY --chown=1000:1000 . .
 # END Builder
 
 FROM python:3.11-alpine