Bump timeout for initial serial read (30s->60s)

TCG is slow and hitting the timeout under initial boot isn't uncommon.
5 jobs for increase-timeout in 27 minutes and 52 seconds (queued for 1 second)
Status Name Job ID Coverage
  Lint
passed shellcheck #10828

00:00:10

passed shfmt #10829

00:00:12

 
  Build
passed build #10830

00:23:41

 
  Test
passed test-cloudimg-qemu #10832

00:03:58

passed test-vagrant-boxes-format #10831

00:00:42