chore(auth): require workflow v0.57.2

[intel352]

Summary

• bump workflow-plugin-auth's Workflow SDK dependency to v0.57.2
• raise plugin minEngineVersion to 0.57.2 so v0.2.5 advertises the engine release containing strict remote plugin config sanitization

Verification

• PLUGIN_MANIFEST_EXPECT_VERSION=0.2.5 GOWORK=off go test ./internal -run TestIntegration_PluginManifestAndStepTypes -count=1
• GOWORK=off go test ./internal
• git diff --check