fix: Update CITATION.cff (#2009)

CITATION.cff

@@ -1,5 +1,8 @@
 cff-version: 1.2.0
 message: "If you use this software, please cite it as below."
+title: "Letta"
+url: "https://github.com/letta-ai/letta"
+preferred-citation:
   type: article
   authors:
   - family-names: "Packer"
@@ -16,12 +19,7 @@ authors:
     given-names: "Ion"
   - family-names: "Gonzalez"
     given-names: "Joseph E"
-title: "MemGPT: Towards LLMs as Operating Systems"
   journal: "arXiv preprint arXiv:2310.08560"
-year: 2023
   month: 10
-identifiers:
-  - type: arxiv
-    value: "2310.08560"
-abstract: "Towards LLMs as Operating Systems"
-url: "https://arxiv.org/abs/2310.08560"
+  title: "MemGPT: Towards LLMs as Operating Systems"
+  year: 2023