Merge pull request #352 from heroku/ignore-engines

ignore engine incompatibilities, this is a dev warning

lib/dependencies.sh

@@ -33,7 +33,7 @@ yarn_node_modules() {
   # according to docs: "Verifies that versions of the package dependencies in the current project’s package.json matches that of yarn’s lock file."
   # however, appears to also check for the presence of deps in node_modules
   # yarn check 1>/dev/null
-  yarn install --pure-lockfile 2>&1
+  yarn install --pure-lockfile --ignore-engines 2>&1
 }
 
 npm_node_modules() {