Travis: Add cargo cache

tmandry · tmandry · commit eb2282f731c2 · 2019-01-14T16:59:46.000-06:00
diff --git a/.travis.yml b/.travis.yml
@@ -2,6 +2,7 @@ language: rust
 rust:
   - beta
   - nightly
+cache: cargo
 script:
   # RUSTC_BOOTSTRAP enables e.g. #![feature] on beta
   - rustup component add rustfmt
