github: workflows: fix yaml error for issue close workflow

Fixes the following workflow action.

Run yamllint -f parsable -d "$yamllint_config" --strict .github/workflows/*.yml *.yml

yamllint -f parsable -d "$yamllint_config" --strict .github/workflows/*.yml *.yml
  shell: /usr/bin/bash -e {0}
  env:
    yamllint_config: {extends: default, rules: {line-length: {max: 100}}}
Warning: orkflows/close-stale.yml:3:1: [warning] truthy value should be one of [false, true] (truthy)
Error: Process completed with exit code 2.

Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>

Author: lrgirdwo

.github/workflows/close-stale.yml

@@ -1,6 +1,7 @@
 ---
 name: "Close stale issues"
-on:
+# yamllint disable-line rule:truthy
+on: [true]
   schedule:
     - cron: "30 1 * * *"