Index: diffus/Cargo.toml
===================================================================
--- diffus.orig/Cargo.toml
+++ diffus/Cargo.toml
@@ -33,7 +33,7 @@ version = "=0.10.0"
 optional = true
 
 [dependencies.indexmap]
-version = "1"
+version = "2"
 optional = true
 
 [dependencies.itertools]
