bump version to 0.20.1

Author: apoelstra

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "secp256k1"
-version = "0.20.0"
+version = "0.20.1"
 authors = [ "Dawid Ciężarkiewicz <dpc@ucore.info>",
             "Andrew Poelstra <apoelstra@wpsoftware.net>" ]
 license = "CC0-1.0"
@@ -56,4 +56,4 @@ required-features = ["rand"]
 
 [workspace]
 members = ["secp256k1-sys"]
-exclude = ["no_std_test"]
+exclude = ["no_std_test"]