chore: remove GK lockfile and bump node versions in testing

fix: update devdeps

fix: drop node 6 from test matrix, we are still copmpatbile tho, this is for standard

chore: ditch standard, so we can support older node versions in testing

chore: use older npm version so we can support older nodes

chore: master branch builds only

chore: prefer npm install to npm ci

nodejs/node#29841

chore: newer npm after all

chore: no node 6 then grmpf

chore: re-add standard

Author: janl

.travis.yml

@@ -1,13 +1,12 @@
 language: "node_js"
 node_js:
-  # keep latest first, so gk-lockfile can work its magic
-  # https://github.com/greenkeeperio/greenkeeper-lockfile#testing-multiple-node-versions
+  - 14.0
+  - 12.0
+  - 10.0
   - 8.0
-  - 6.0
-  - node
-before_install:
-# package-lock.json was introduced in npm@5
-- npm install -g npm@5
-- npm install -g greenkeeper-lockfile@1
-before_script: greenkeeper-lockfile-update
-after_script: greenkeeper-lockfile-upload
+install:
+  - npm install
+# Avoid double build on PRs (See https://github.com/travis-ci/travis-ci/issues/1147)
+branches:
+  only:
+    - master