Remove duplicate entry in CITATION.cff. Fixes LLNL#469

Author: daboehme

CITATION.cff

@@ -47,8 +47,6 @@ preferred-citation:
   - family-names: "Beckingsale"
     given-names: "David"
     orcid: "https://orcid.org/0000-0003-2545-4837"
-  - family-names: "Boehme"
-    given-names: "David"
   - family-names: "Bremer"
     given-names: "Peer-Timo"
     orcid: "https://orcid.org/0000-0003-4107-3831"