Remove old dependencies

[bnavigator]

Description

The feature or problem addressed by this PR

Having both

python = "^3.9"
# and
importlib-metadata = {version = ">=1.7.0", python = "<3.8"}
importlib-resources = {python = "<3.9", version = "*"}

does not make sense.

What your changes do and why you chose this solution

Remove the old dependencies

Checklist

• [x] Checked that no other issues or pull requests exist for the same issue/change
• [ ] Added tests covering the new functionality
• [x] Updated documentation OR the change is too minor to be documented
• [x] ~~Updated CHANGELOG.md OR~~ changes are insignificant