Test more Go versions

Author: kyleconroy

.github/workflows/ci.yml

@@ -19,11 +19,14 @@ jobs:
         - 5432:5432
         # needed because the postgres container does not provide a healthcheck
         options: --health-cmd pg_isready --health-interval 10s --health-timeout 5s --health-retries 5
+    strategy:
+      matrix:
+        go: ['1.17', '1.16', '1.15']
     steps:
     - uses: actions/checkout@v2.3.4
     - uses: actions/setup-go@v2
       with:
-        go-version: '1.17'
+        go-version: ${{ matrix.go }}
     - run: go build ./...
     - run: go build ./...
       working-directory: tests