workflows: Ensure a label change re-triggers the actions

This is needed in order to ensure that, for instance, if `force-skip-ci`
label is either added or removed later, the jobs related to the actions
will be restarted and accordingly checked.

Signed-off-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>

.github/workflows/snap.yaml

@@ -1,5 +1,14 @@
 name: snap CI
-on: ["pull_request"]
+on:
+  pull_request:
+    types:
+      - opened
+      - synchronize
+      - reopened
+      - edited
+      - labeled
+      - unlabeled
+
 jobs:
   test:
     runs-on: ubuntu-20.04