Pin conftest to v0.20.0

[jalseth]

Pulling from GCS buckets is broken in v0.21.0 (currently latest) so this pins conftest to the latest working version until it is fixed upstream.

Edit -- examples:

$ docker run --rm -it -v $PWD:/data -e GOOGLE_APPLICATION_CREDENTIALS="/data/gcs.json" instrumenta/conftest:v0.21.0 pull gcs::https://www.googleapis.com/storage/v1/redacted-bucket/policy
Error: download policies: client get: error downloading 'https://www.googleapis.com/storage/v1/yes-k8s-policy/policy': RemoveAll .: invalid argument

$ echo $?
1

$ docker run --rm -it -v $PWD:/data -e GOOGLE_APPLICATION_CREDENTIALS="/data/gcs.json" instrumenta/conftest:v0.20.0 pull gcs::https://www.googleapis.com/storage/v1/redacted-bucket/policy

$ echo $?
0

[github-actions]

Conftest has identified issues with your resources

The following warnings were identified. These are issues that indicate the resources are not following best practices.

• WARN - .github/test/resources/test.yaml - a warning! you should probably fix this

[ducksauz]

🧷