Can't view workflows using postgres in 1.7 and 1.8

[AydinE]

Describe the bug

Can no longer go to the Workflows page in later versions of Orchard 1.7 and any version of Orchard 1.8 if the database you are using is postgres.

Likely related to this commit that reworked the way the workflows are loaded in as I wasn't having this issue in early versions of Orchard 1.7 preview builds: Commit

To Reproduce

Steps to reproduce the behavior:

1. Create a new tenant
2. Use Postgres as the database
3. Try to view the workflows page

Expected behavior

The workflows page shows up

Screenshots

[AydinE]

Didn't show up while searching but found issue already reported: #14334