chore: add go1.16 version

.travis.yml

@@ -1,26 +0,0 @@
-language: go
-
-jobs:
-  fast_finish: true
-  include:
-  - go: 1.16.x
-  - go: master
-
-install:
-  - go get -t -v -d
-  - go get github.com/campoy/embedmd
-
-script:
-  - embedmd -w *.md
-  - go test -v -covermode=atomic -coverprofile=coverage.out
-
-after_success:
-  - bash <(curl -s https://codecov.io/bash)
-
-notifications:
-  webhooks:
-    urls:
-      - https://webhooks.gitter.im/e/acc2c57482e94b44f557
-    on_success: change
-    on_failure: always
-    on_start: never