ci: drop Node 6 support, add Node 12

BREAKING CHANGE: Node 6 support has been dropped due to EOL.

Author: whizark

.travis.yml

@@ -3,10 +3,10 @@ sudo: false
 language: node_js
 
 node_js:
-    - 6
     - 8
     - 10
     - 11
+    - 12
 
 matrix:
     fast_finish: true
@@ -40,7 +40,7 @@ deploy:
       api_key:
           secure: DGgGAEBf2wi/wXtHHpx9aI753iNvSoxWQPiKVmCQgT6PUqnLHL4bwqq9J1WxDyeiPo31UyY8GCUzH4BVIrl/lmaVGRu3OXtJP4jnqK6B/VRS4aYJpA53hypIW46eWluXCjCxwnt+gRLF89Aqwuh6HJWOXspdveD0sGqzeT6NBq39hhA+NiuEnKNlsS0COCf+YjK0yw9Mj7Q67F6gnRXBqHsaObNgt2qoEb9Biui42iaMAldtb4LDErMON5K3V2Pwk+oQHIsNq1Efk9BlnHAJwD08RH+8JNYluSPskJO8+4SP3AdDo7EXb5luA48VdT3PXajA4kKjCjgWOqbfJzkTbRz5f7DJo7+M5YNBoHf+wEjhGat/aegdbJuRu2Sm9BCzVM7e2JZjCXa5vVH8LxNCLniyMv9Hf6tMTm25sUPzdOHWrYvMQ86+wLjpzNySWcilp3CSlQd+IB7ysVz6h7AdtXMtosNXf19caC0pbsN6kt3fxzzRqdUadP2r9Na+aWhJAJtRsNDaYCxmO5nqS3hcWEhS6i9RWVOGQ/onNrrrA+MtH8ImBK9MqGKwMzY4t51Rx7QRTMRqu01/zeELdWIK3hpTyCeBLlbQG8tV5WIjHLTiFJo8HoQ7rJoXRl5TrymarNUccaR8+UvWFuAcAufoGW528L1I2rGQx6hSGamd238=
       on:
-          node: 8
+          node: 12
           repo: whizark/commitlint-config-cz
           branch: master
           tags: true