Dear Maintainer,

The doc package wants a specific version of the main package and
therefore doesn't let it upgrade. Probably some sort of minor
misconfiguration.

$ sudo apt upgrade python3-biopython --dry-run

Calculating upgrade... Error!
Error: Unable to satisfy dependencies. Reached two conflicting assignments:
   1. python-biopython-doc:amd64 is selected for install
   2. python-biopython-doc:amd64 Recommends python3-biopython (= 1.88+dfsg-2)
      but none of the choices are installable:
      - python3-biopython:amd64=1.88+dfsg-2 is not selected for install because:
        1. python3-biopython:amd64=1.88+dfsg-2+b1 is selected as an upgrade
        2. python3-biopython:amd64=1.88+dfsg-2+b1 conflicts with other versions of itself