Implement sentry, use pre-built docker image

[Xpirix]

This is mainly a fix for #91

Changes summary

• Implement sentry SDK for the Django project
• Use a pre-built docker image for the qgisfeed service
• GH workflow to push the image to the docker hub when pushing a new tag
• Update some of the packages in requirements

[timlinux]

LGTM

[timlinux]

BTW QGIS should have its own sentry account instead of using kartozas