The 'expression' field is now a list of strings
There are three TOML files in not-approved/ that have multiple SPDX
expressions for the license entry in this project. So change the
expression field to be a list of strings. Update the import scripts,
the README, the template, and all of the other TOML files.
Signed-off-by: David Cantrell <dcantrell@redhat.com>