Upgrade dompdf and then test and ensure it works

We currently have dompdf 0.6.2 version or lower. We will be upgrading our server from Apache3 to Apache4 and in order for pdf delivery to work we need the latest version of dompdf.

The job is:
1. Install, upgrade or migrate (whichever is needed) so we have the latest dompdf version which is 0.82
2. Test to ensure it works. We can then test to send a pdf out.
3. Ensure no code/php errors and dompdf works

Must be done at a set time to avoid issues with actual live work.