ci: fix travis ci (#559)

abetomo · web-flow · commit 329a4102fea4 · 2021-03-31T10:48:34.000+02:00
It seems that npm is outdated and the test is failing.
diff --git a/.travis.yml b/.travis.yml
@@ -4,6 +4,8 @@ node_js:
   - "lts/*"
   - "node"
 
+install: npm i -g npm
+
 cache:
   directories:
     - node_modules
