fix(CI): only run semantic-release on push-to-master (not on pull req…

…uests) (awslabs#184)

* fix(CI): only run semantic-release on push-to-master (not on pull
    requests)

* fix(CI): removed builds for older versions of Go

.travis.yml

@@ -2,9 +2,7 @@ language: go
 
 matrix:
   include:
-    - go: "1.10.x"
-      script: go test -v ./...
-    - go: "1.11.x"
+    - go: "1.12.x"
       script: go test -v -mod=vendor ./...
 
 env:
@@ -27,6 +25,7 @@ jobs:
 
     # Define the release stage that runs semantic-release
     - stage: release
+      if: branch = master AND type = push
       language: node_js
       node_js: lts/*
       before_install: skip