Update debian/control.in throughout for Debian Bullseye

This merge requests makes a few updates to the debian/control.in files based on recommendations from @steffen.grunewald. In particular:

• X-Python-Version -> X-Python3-Version
• add dh-python dependency where needed

In addition, some tidying up in the gstlal-burst dependencies as well as updating the maintainer to myself.

@madeline-wade, I have also updated gstlal-calibration as well to reflect these changes.