composer: Use more obvious spellcheck icon

The previous dictionary icon did not immediately indicate
a connection to spellchecking. This could lead to the
impression that Geary has no spellchecking support if one
doesn't look carefully enough.

Now we use an icon that directly symbolizes spellchecking.
5 jobs for wip/christopherdavis/change-spellcheck-icon in 25 minutes and 43 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Build
passed #273107
fedora

00:08:55

passed #273108
ubuntu

00:11:06

 
  Test
passed #273109
flatpak

00:14:04

 
  Deploy
passed #273110
review

00:00:31

manual #273111
allowed to fail manual
stop_review