remove yarn

test/test_latest.sh

@@ -1,2 +1,2 @@
 #!/bin/sh
-yarn -v
+npm -v

test/test_npmci.sh

@@ -4,6 +4,6 @@ npmci -v
 # check if we can use lts
 npmci install lts
 
-# check if yarn picks it up
-npmci command yarn global add npmts
+# check if npm picks it up
+npmci command npm install -g npmts
 npmci command npmts -v

test/test_stable.sh

@@ -1,3 +1,3 @@
-# test yarn
-yarn global add npmts
+# npm
+npm install -g npmts
 npmts -v