There is no need to disable Python packages for Python versions that are
no longer in Nixpkgs.
This change was generated using the following script:

    pattern='^\s*disabled\s*=\s*pythonOlder\s*"3\.\([0-9]\|10\)"\s*;\s*$'
    for f in $(find -name '*.nix'); do
        grep -q "$pattern" "$f" || continue
        sed -i "/$pattern/d" "$f"
        if [ $(grep -c pythonOlder "$f") == 1 ]; then
            sed -i '/^\s*pythonOlder,\s*$/d' "$f"
        fi
        nixfmt "$f"
    done

This commit was created by a combination of scripts and tools:
- an ast-grep script to prefix things in meta with `lib.`,
- a modified nixf-diagnose / nixf combination to remove unused `with
lib;`, and
- regular nixfmt.

Co-authored-by: Wolfgang Walther <walther@technowledgy.de>