Hints for opencpn in main

org.opencpn.OpenCPN ⚙ amd64 ⚙ arm64 ⚙ armhf ⚙ loong64 ⚙ ppc64el ⚙ riscv64 ⚙ s390x

asv-release-time-missing
opencpn.appdata.xml:41 - date
The release entry is missing either the `date` (preferred) or the `timestamp` property.