[CI] Only cache .cargo dir

bjorn3 · bjorn3 · commit 91b058de9409 · 2019-07-03T16:27:06.000+02:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,6 +1,8 @@
 sudo: false
 language: rust
-cache: cargo
+cache:
+  directories:
+    - $HOME/.cargo
 
 os:
   - linux
