[python] Fix dependencies of pyproject.toml for ARM SDK (#8349)

Author: msyyc

.chronus/changes/fix-pyproject-2025-8-3-13-40-25.md

@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@typespec/http-client-python"
+---
+
+Fix dependencies of pyproject.toml for ARM SDK

packages/http-client-python/generator/pygen/codegen/templates/packaging_templates/pyproject.toml.jinja2

@@ -43,7 +43,7 @@ dependencies = [
     {% else %}
     "isodate>={{ VERSION_MAP['isodate'] }}",
     {% endif %}
-    {% if options.get('azure_arm') %}
+    {% if options.get('azure-arm') %}
     "azure-mgmt-core>={{ VERSION_MAP['azure-mgmt-core'] }}",
     {% elif code_model.is_azure_flavor %}
     "azure-core>={{ VERSION_MAP['azure-core'] }}",