Delete a scanner for a technology this project does not use

prisma.yml has failed on every push to master since the day it was
added, and could never have done anything else. It is GitHub's sample
Prisma Cloud workflow, added and never configured: it wants three
secrets this repository does not have (Prisma Cloud is a paid Palo Alto
product), it still carries the template's literal asset_name of
'my-asset-name', and it scans for CloudFormation templates.

There is no CloudFormation here. No Terraform, no Bicep, not even a
docker-compose. This is a Windows C++ mail server; there is no
infrastructure-as-code in the tree for an IaC scanner to read.

So it was a scanner for a technology the project does not use, wired to
a service the project does not subscribe to, marking every commit with
a red X. Deleting it costs nothing and removes a permanently failing
check - and a check that is always red is worse than no check, because
it trains everyone to ignore the colour.

The SHA pinning it received an hour ago was correct work on a file that
should not exist; that pinning survives in the two workflows that
genuinely needed it.

Author: chrisholloway5