poetry 2.0 no longer has export, install it for certbot-josepy (#12241)

* poetry 2.0 no longer has export, install it for certbot-josepy

* Update .github/downstream.d/certbot-josepy.sh

Co-authored-by: Alex Gaynor <alex.gaynor@gmail.com>

---------

Co-authored-by: Alex Gaynor <alex.gaynor@gmail.com>

.github/downstream.d/certbot-josepy.sh

@@ -6,6 +6,7 @@ case "${1}" in
         cd josepy
         git rev-parse HEAD
         curl -sSL https://install.python-poetry.org | python3 -
+        "${HOME}/.local/bin/poetry" self add poetry-plugin-export
         "${HOME}/.local/bin/poetry" export -f constraints.txt --dev --without-hashes -o constraints.txt
         pip install -e . pytest -c constraints.txt
         ;;