Lock ROOT and FairMQ versions for online environment (EPN builds)

Author: ehellbar

defaults-o2-epn.sh

@@ -48,6 +48,10 @@ overrides:
       - O2
       - fmt
       - ucx   # this one added
+  FairMQ:
+    tag: "v1.9.2"
+  ROOT:
+    tag: "v6-32-06-alice9"
 ---
 # This file is included in any build recipe and it's only used to set
 # environment variables. Which file to actually include can be defined by the