Merge #454: Pin serde to 1.0.142

cd8da9e Pin serde to 1.0.142 (sanket1729)

Pull request description:

  Similar to rust-bitcoin/rust-bitcoin#1178

ACKs for top commit:
  apoelstra:
    utACK cd8da9e

Tree-SHA512: 14de10187973272cacc1b6278f32fec2e266d1507a4548fe224f146b74bfcf6b2b5e8fb61cae66d7b13232bb073c88ca1a6f94a36def75773382cef975a101f0

Author: apoelstra

contrib/test.sh

@@ -10,6 +10,9 @@ then
     alias cargo="cargo +$TOOLCHAIN"
 fi
 
+cargo update -p serde --precise 1.0.142
+cargo update -p serde_derive --precise 1.0.142
+
 cargo --version
 rustc --version