HELM_DIFF_IGNORE_UNKNOWN_FLAGS seems to be ignored in v3.9.2

[deiga]

Hello,

We have added --force to helm diff upgrade a few weeks ago and added HELM_DIFF_IGNORE_UNKNOWN_FLAGS=true to the environment.

Today our client auto-updated to 3.9.2 from 3.8.1 and we are getting this error in our CI.

[2024-01-18T19:15:22.172Z] + helm diff -C7 upgrade --allow-unreleased --force --values helm/values-eu-qa.yaml --values helm/values-pr.yaml ...

[2024-01-18T19:15:22.172Z] Error: unknown flag: --force

[2024-01-18T19:15:22.172Z] Usage:

[2024-01-18T19:15:22.172Z]   diff upgrade [flags] [RELEASE] [CHART]

[deiga]

We reverted back to 3.8.1 and it works again

[yxxhero]

@deiga PR is welcome.

[yxxhero]

#499