Use curlimages/curl for php test pod

[tasuku43]

Summary

This pull request updates the default Helm test Pod image in the PHP chart to use curlimages/curl.
The previously used image, appropriate/curl, is now archived and no longer maintained, and it only provides AMD64 builds. As a result, it does not run on ARM-based runners or clusters.
By switching to curlimages/curl—a maintained, multi-architecture image—the chart becomes compatible with both AMD64 and ARM environments.

Changes

• Replaced appropriate/curl with curlimages/curl as the default test Pod image

  • Addresses maintenance issues (upstream archived)
  • Resolves architecture limitation (ARM images not available)

• Added test.image.repository and test.image.tag values to allow customized image overrides

• Updated README to document the new configuration options

---

Testing

The change was verified using helm install followed by helm test.

$ helm install php-test ./php --set service.port=80
NAME: php-test
LAST DEPLOYED: Wed Nov 26 11:34:12 2025
NAMESPACE: default
STATUS: deployed
REVISION: 1
NOTES:
1. Get the application URL by running these commands:
     NOTE: It may take a few minutes for the LoadBalancer IP to be available.
           You can watch the status of by running 'kubectl get svc -w php-test'
  export SERVICE_IP=$(kubectl get svc --namespace default php-test -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
  echo http://$SERVICE_IP:80

$ helm test php-test --timeout 2m
NAME: php-test
LAST DEPLOYED: Wed Nov 26 11:34:12 2025
NAMESPACE: default
STATUS: deployed
REVISION: 1
TEST SUITE:     php-test-test
Last Started:   Wed Nov 26 11:35:11 2025
Last Completed: Wed Nov 26 11:35:17 2025
Phase:          Succeeded

The test suite ran successfully, confirming that the new image and configuration function as expected.

[cw-atkhry]

LGTM!