Fix rustup invocation

ian-h-chamberlain · ian-h-chamberlain · commit e28f80889e81 · 2019-12-01T14:07:18.000-05:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,7 +1,7 @@
 language: rust
 
 before_install:
-  - rustup component clippy rustfmt
+  - rustup component add clippy rustfmt
 
 rust:
   - stable
