ci: use go 1.15 & 1.16 on CI (#4)

.github/workflows/ci.yml

@@ -5,22 +5,25 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
+        go-version: [1.15.x, 1.16.x]
         os: [ubuntu-latest, windows-latest, macos-latest]
     runs-on: ${{ matrix.os }}
-
     steps:
-      - name: Set up Go 1.13
+      -
+        name: Set up Go
         uses: actions/setup-go@v1
         with:
-          go-version: 1.13
-
-      - name: Check out code into the Go module directory
+          go-version: ${{ matrix.go-version }}
+      -
+        name: Check out code into the Go module directory
         uses: actions/checkout@v2
-
-      - name: Verify dependencies
+        with:
+          fetch-depth: 0
+      -
+        name: Verify dependencies
         run: go mod verify
-
-      - name: Build
+      -
+        name: Build
         shell: bash
         run: |
           go build -v ./cmd/tog