Limit compatibility to Helm =>v3.0.0,<4.0.0 (#1039) (#1071)

This is a backport of PR #1039 as merged into main (13791ec).
SUMMARY
Helm v4 is a major version with backward-incompatible changes, including to the flags and output of the Helm CLI and to the SDK. This version is currently not supported in the kubernetes.core. This PR is related to #1038 and is a short-term solution to mark compatibility explicitly
ISSUE TYPE

Bugfix Pull Request
Docs Pull Request

COMPONENT NAME

helm
helm_template
helm_info
helm_repository
helm_pull
helm_registry_auth
helm_plugin
helm_plugin_info

ADDITIONAL INFORMATION
Added `validate_helm_version()`` method to AnsibleHelmModule that enforces version constraint >=3.0.0,<4.0.0.
Fails fast with clear error message: "Helm version must be >=3.0.0,<4.0.0, current version is {version}"
Some modules (i.e. helm_registry_auth) technically is compatible with Helm v4, but validation was added to all helm modules.
Partially coauthored by GitHub Copilot with Claude Sonnet 4 model.
Addresses issue #1038

Reviewed-by: Bianca Henderson <beeankha@gmail.com>
Reviewed-by: Mike Graves <mgraves@redhat.com>

README.md

@@ -30,6 +30,10 @@ A collection may contain metadata that identifies these versions.
 PEP440 is the schema used to describe the versions of Ansible.
 <!--end requires_ansible-->
 
+### Helm Version Compatibility
+
+Helm modules in this collection are compatible with Helm v3.x and are not yet compatible with Helm v4. Individual modules and their parameters may support a more specific range of Helm versions.
+
 ### Python Support
 
 * Collection supports 3.9+