Merge pull request #68 from Davidson-Souza/bump-0.4.0

bump version to 0.4.0 for new release

Author: Davidson-Souza

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "rustreexo"
-version = "0.3.0"
+version = "0.4.0"
 authors = ["Calvin Kim <calvin@kcalvinalvin.info>"]
 edition = "2018"
 description = "A Rust implementation of Utreexo"