derive 'Default' where possible

3 jobs for refactor/derive-default in 11 minutes and 11 seconds (queued for 4 seconds)
latest
Status Name Job ID Coverage
  Build
passed rust-latest #36601
amd64

00:10:52

passed rust-latest-async-std #36602
amd64

00:01:01

passed rust-nightly #36603
amd64

00:11:11