Bump version from 2.20 to 2.21

Author: PBrdng

Project.toml

@@ -1,7 +1,7 @@
 name = "HomotopyContinuation"
 uuid = "f213a82b-91d6-5c5d-acf7-10f1c761b327"
 authors = ["Sascha Timme <sascha@timme.xyz>", "Paul Breiding <pbrdng@gmail.com>"]
-version = "2.20"
+version = "2.21"
 
 [deps]
 Arblib = "fb37089c-8514-4489-9461-98f9c8763369"