github-actions: Update mate-desktop dependency

Author: cwendling

.github/workflows/build.yml

@@ -15,7 +15,7 @@ concurrency:
   cancel-in-progress: true
 
 env:
-  MATE_PANEL_DEP: 1.27.1
+  MATE_PANEL_DEP: 1.28.2
   CONFIGURE_FLAGS: --enable-compile-warnings=maximum
   CFLAGS: -g -O2 -Werror=pointer-arith -Werror=implicit-function-declaration
   JOBS: 2