[FIX] test_assetsbundle: handle readonly files

If the Odoo server runs with its sources read-only
for itself, this is not possible for the server
to touch the files contained in the assets.

In such a case, instead of touching the file,
we alter the attachment checksum, to simulate
a change within the modified date.

However, in such a case, we can only test that the
bundle is well generated again.
We can no longer check the change of version and modified date,
since the modified date of the files have not changed,
and therefore the checksum (which is based on the files
modified date, among others) neither.

0 files changed, 0 insertions, 0 deletions