nightly-build: attempt to no longer choke on existing file When we run the job multiple time, the upload step fails because the file always exists. So we pass the `--skip-existing` flag that is supposed to help with that? when supported. This might have no effect outside of upload to PyPI as the doc says: Continue uploading files if one already exists. (Only valid when uploading to PyPI. Other implementations may not support this.)

--- a/contrib/heptapod-ci.yml	Fri Feb 28 17:54:12 2025 +0400
+++ b/contrib/heptapod-ci.yml	Mon Mar 10 14:28:33 2025 +0100
@@ -702,5 +702,6 @@
       upload
       --verbose
       --repository-url ${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/pypi
+      --skip-existing
       wheels/*/*/*/*.whl
       wheels/*/*.whl