Work around another variant of invalid JSON

This time it's extra commas at the end of objects, brought to you by
Eventbrite. So far their emails contained valid JSON, but the affected
one does not contain a location, so possibly breaking their template.
1 job for v20.11.90 in 8 minutes and 27 seconds (queued for 480 minutes and 49 seconds)
latest
Status Job ID Name Coverage
  Build
passed #80260
build_clazy_clang_tidy

00:08:27