Add serde+no_std tests to CI

Author: pitdicker

.travis.yml

@@ -29,6 +29,7 @@ script:
   - cargo test
   - cargo test --tests --no-default-features
   - cargo test --features serde-1
+  - cargo test --tests --no-default-features --features=serde-1
   - cargo test --manifest-path rand-derive/Cargo.toml
 
 env:

appveyor.yml

@@ -37,4 +37,5 @@ test_script:
   - cargo test --features serde-1
   - cargo test --features nightly
   - cargo test --tests --no-default-features --features=alloc
+  - cargo test --tests --no-default-features --features=serde-1
   - cargo test --manifest-path rand-derive/Cargo.toml