MAINTAINERS: add myself as a collaborator for llext

Add @pillo79 as a collaborator for llext development.

Signed-off-by: Luca Burelli <l.burelli@arduino.cc>

MAINTAINERS.yml

diff --git a/MAINTAINERS.yml b/MAINTAINERS.yml
index 5523a72..c14008e 100644
--- a/MAINTAINERS.yml
+++ b/MAINTAINERS.yml
@@ -3975,6 +3975,7 @@
     - teburd
   collaborators:
     - lyakh
+    - pillo79
   files:
     - samples/subsys/llext/
     - include/zephyr/llext/