Bump to 0.3.21
diff --git a/Cargo.toml b/Cargo.toml
index da5d3dc..49e6e18 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 
 name = "gcc"
-version = "0.3.20"
+version = "0.3.21"
 authors = ["Alex Crichton <alex@alexcrichton.com>"]
 license = "MIT/Apache-2.0"
 repository = "https://github.com/alexcrichton/gcc-rs"