chore: Fix travis config

used https://config.travis-ci.com/explore to verify

.travis.yml

@@ -13,9 +13,9 @@ git:
   depth: 1
 
 cache:
-  - pip
-  - npm
-  - yarn
+  pip: true
+  npm: true
+  yarn: true
   directories:
     # we also need to cache folder with Cypress binary
     # https://docs.cypress.io/guides/guides/continuous-integration.html#Caching