Fix prometheus_blackbox_exporter_endpoints select

Enabled items under prometheus_blackbox_exporter_endpoints_kayobe were
not picked up because the attribute gets set to `enabled: 'True'`,
rather the than `enabled: true` that the default values get. Likely a
similar issue to this:
ansible/ansible#11905 (comment)

Author: MoteHue

etc/kayobe/kolla/inventory/group_vars/prometheus-blackbox-exporter

@@ -9,7 +9,7 @@
 prometheus_blackbox_exporter_endpoints: >-
   {{ (prometheus_blackbox_exporter_endpoints_kayobe | default([]) +
   prometheus_blackbox_exporter_endpoints_default) |
-  selectattr('enabled', 'true') |
+  selectattr('enabled', 'match', 'true|True') |
   map(attribute='endpoints') | flatten |
   union(prometheus_blackbox_exporter_endpoints_custom) |
   unique | select | list }}

releasenotes/notes/fix-prometheus_blackbox_exporter_endpoints-selectattr-2edb1bc7e775a30a.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixes an issue where enabled endpoints under
+    ``prometheus_blackbox_exporter_endpoints_kayobe`` were not picked up when
+    templating out ``prometheus_blackbox_exporter_endpoints``.