fix: update the version of './contrib/cat-videos-example/docker-compose.yml'

[lmt-swallow]

Related issue

I got the following message when I tried to run "cat videos example" in the way this guide explains:

$ git clone [email protected]:ory/keto.git && cd keto
(blah blah)
$ docker-compose -f contrib/cat-videos-example/docker-compose.yml up --build
ERROR: The Compose file './contrib/cat-videos-example/docker-compose.yml' is invalid because:
services.keto.volumes contains an invalid type, it should be a string
services.keto-init.volumes contains an invalid type, it should be a string

This issue was originally the one reported in the pull request #549, and the pull request fixed the issue of ./docker-compose-postgres.yml indeed. However, ./contrib/cat-videos-example/docker-compose.yml still seems broken.

Proposed changes

Update version: '3' to version: '3.2' as suggested in #549 .

Checklist

• I have read the contributing guidelines.
• I have read the security policy.
• I confirm that this pull request does not address a security
  vulnerability. If this pull request addresses a security. vulnerability, I
  confirm that I got green light (please contact
  [email protected]) from the maintainers to push
  the changes.
• I have added tests that prove my fix is effective or that my feature
  works.
• I have added or changed the documentation.

Further comments

[CLAassistant]

All committers have signed the CLA.

[aeneasr]

Awesome, thank you!