Bump pythia6 to 428-alice2 (#2578)

Co-authored-by: hristov <[email protected]>

Author: pzhristov

pythia6.sh

@@ -1,7 +1,7 @@
 # a pythia6 recipe based on the one from FairROOT
 package: pythia6
 version: "%(tag_basename)s"
-tag: "428-alice1"
+tag: "428-alice2"
 source: https://github.com/alisw/pythia6.git
 requires:
   - GCC-Toolchain:(?!osx)