Fix appveyor

Author: weiznich

.appveyor.yml

@@ -46,7 +46,7 @@ test_script:
   - cd ../diesel
   - cargo test --features "%backend% extras"
   - cd ../diesel_proc_macro
-  - cargo test --features "%backend dotenv_macro"
+  - cargo test --features "%backend% dotenv_macro"
   - cd ../diesel_cli
   - cargo test --no-default-features --features "%backend%"
   - cd ../diesel_tests