chore: Use proper version in cff file

CITATION.cff

@@ -2,13 +2,13 @@
 # CITATION file created with {cffr} R package, v0.5.0
 # See also: https://docs.ropensci.org/cffr/
 # -----------------------------------------------------------
- 
+
 cff-version: 1.2.0
 message: 'To cite package "igraph" in publications use:'
 type: software
 license: GPL-2.0-or-later
 title: 'igraph: Network Analysis and Visualization'
-version: 1.99.99.9002
+version: 2.0.0
 abstract: Routines for simple graphs and network analysis. It can handle large graphs
   very well and provides functions for generating random and regular graphs, graph
   visualization, centrality methods and much more.
@@ -86,7 +86,7 @@ references:
   - family-names: Müller
     given-names: Kirill
   year: '2024'
-  notes: R package version 1.99.99.9002
+  notes: R package version 2.0.0
   doi: 10.5281/zenodo.7682609
   url: https://CRAN.R-project.org/package=igraph
 - type: software