Add back 1.14.x testing

Author: mheffner

.github/workflows/build.yml

@@ -4,9 +4,12 @@ on: push
 jobs:
   build:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        go: ['1.13.x', '1.14.x']
     steps:
     - uses: actions/checkout@master
     - uses: actions/setup-go@v1
       with:
-        go-version: '1.13.x' # The Go version to download (if necessary) and use.
+        go-version: ${{ matrix.go }} # The Go version to download (if necessary) and use.
     - run: make deps build test