ci: drop Go-1.9+1.10, add Go-1.12.x and Go-1.13.x

Author: sbinet

.travis.yml

@@ -13,16 +13,16 @@ matrix:
  allow_failures:
    - go: master
  include:
-   - go: 1.9.x
+   - go: 1.13.x
      env:
        - TAGS="-tags travis"
-   - go: 1.10.x
+       - COVERAGE="-cover"
+   - go: 1.12.x
      env:
        - TAGS="-tags travis"
    - go: 1.11.x
      env:
        - TAGS="-tags travis"
-       - COVERAGE="-cover"
    - go: master
      env:
        - TAGS="-tags travis"

appveyor.yml

@@ -12,7 +12,7 @@ environment:
   matrix:
     - TARGET: x86_64-pc-windows-gnu
 
-stack: go 1.11
+stack: go 1.13
 
 build_script:
   - go get -v -t -race ./...