Comment 2 for bug 1844987

Same thing, I can't upgrade to 20.04 because of this.

 $ sudo do-release-upgrade
proxy 'false' looks invalid
Checking for a new Ubuntu release
Please install all available updates for your release before upgrading.

 $ sudo apt upgrade calendar-indicator
...

The following packages have unmet dependencies:
 calendar-indicator : Depends: gir1.2-handy-0.0 but it is not installable
                      Depends: yaru-theme-gtk but it is not installable
E: Broken packages

 $ inxi
CPU~8 core Intel Core i7-7820X (-MT-MCP-) speed/max~1514/4500 MHz Kernel~4.15.0-153-generic x86_64 Up~2:52 Mem~9891.4/31657.3MB HDD~3000.6GB(88.9% used) Procs~576 Client~Shell inxi~2.3.56