ci: tags: Add folders covered by openthread tag

openthread tag was used in test specifications, but did not define what
source directories were related to this tag.

Signed-off-by: Robert Lubos <[email protected]>

Author: rlubos

scripts/ci/tags.yaml

@@ -76,6 +76,11 @@ net:
     - drivers/ieee802154/
     - drivers/ptp_clock/
 
+openthread:
+  files:
+    - modules/openthread/
+    - subsys/net/l2/openthread/
+
 posix:
   files:
     - lib/posix/