Add label to exempt specific PRs from stalled labeling

Signed-off-by: Simeon Widdis <sawiddis@amazon.com>

Author: Swiddis

.github/workflows/stalled.yml

@@ -27,3 +27,4 @@ jobs:
           days-before-pr-close: -1
           days-before-issue-close: -1
           exempt-draft-pr: true
+          exempt-pr-labels: 'no-stall'