ref(metrics): Change push_scope to new_scope

`sentry_sdk.push_scope` is soft-deprecated, and will soon be hard-
deprecated (see sentry-python#3347), so replace the `push_scope`
calls with appropriate new API. Here, we use `sentry_sdk.new_scope`,
since we are setting tags for a `capture_message` call.

Closes #74938

src/sentry/sentry_metrics/span_attribute_extraction_rules.py

@@ -20,7 +20,7 @@ def create_extraction_rule_config(request: Request, project: Project, config_upd
             or len(obj["conditions"]) == 0
             or (len(obj["conditions"]) == 1 and obj["conditions"][0] == "")
         ):
-            with sentry_sdk.push_scope() as scope:
+            with sentry_sdk.new_scope() as scope:
                 scope.set_tag("project", project.slug)
                 sentry_sdk.capture_message(
                     "A MetricExtractionRuleConfig without conditions was created.",