Drop support for Python 3.9/new major version 7.0

[stefan6419846]

Python 3.9 is going to be EOL at the end of this month, with the first libraries (like Pillow) already having dropped support for it in their latest releases.

In the past, we supported EOL Python versions for almost another year, causing some issues with tooling (like Dependabot) for example. For this reason, I am thinking about better aligning our release/support schedule with Python itself.

Per our policies, dropping support for Python 3.9 would lead to a new major version 7.0 as well.

The following tasks should be done before the release:

• Stop testing on Python 3.9 (and move cryptography module testing to Python 3.10)
• Update coding-style related packages to the latest version
• Update pre-commit hooks to the latest version
• Adapt any Python 3.9 references and replace them with Python 3.10
• Run pyupgrade
• Replace deprecate* with deprecation*
• Remove code sections marked with deprecation*

Please note that I do not have any direct schedule for this and thus I am open for feedback. My plans are to maybe look into this in February or March 2026.