remove unused secured secrets

.travis.yml

@@ -1,13 +1,8 @@
 language: node_js
 
 node_js:
-  - '8'
+  - '10'
 
 script: "npm run cover"
 
 after_script: "cat ./coverage/lcov.info | ./node_modules/coveralls/bin/coveralls.js"
-
-env:
-  global:
-  - secure: imoswT3Ym3I8iPp9hxTSl0ORrNMziwzJkWCbffeNdLV4QsivY4VCwp0xIFn8efQKCUQPRImbjLhOf05hWzGvjja6PNkjvAv/nHo+4MQYvWvjmMnlAlxDmfu7KatGBDQ0vq6W1FFNjT+h2tMs13IVJFwnE90sWwFbS2htcd3MXM4=
-  - secure: e4MxszpP+BdJF5Qu3iAt+YxuQnHBdbRcVOlTHJqWwzbGCQnK0MG0v2BTLT4jyqFB1Qo3qMBF+PgGu+p1D8502MivqWzmKmGq6Qz98twnAE72J7W//LzwU9y7i1b8Zg42Ky556314BjzAPSO5c7fHiVn4I6seBerffmiYbS3UyiU=