use go 1.12

Signed-off-by: hongming <talonwan@yunify.com>

vendor/github.com/miekg/dns/.travis.yml

@@ -0,0 +1,19 @@
+language: go
+sudo: false
+
+go:
+  - 1.10.x
+  - 1.11.x
+  - 1.12.x
+  - tip
+
+before_install:
+  # don't use the miekg/dns when testing forks
+  - mkdir -p $GOPATH/src/github.com/miekg
+  - ln -s $TRAVIS_BUILD_DIR $GOPATH/src/github.com/miekg/ || true
+
+script:
+  - go test -race -v -bench=. -coverprofile=coverage.txt -covermode=atomic ./...
+
+after_success:
+  - bash <(curl -s https://codecov.io/bash)