fix go version & go mod

.github/workflows/coverage.yml

@@ -5,21 +5,21 @@ on:
     branches: [ main ]
   pull_request:
     branches: [ main ]
-  workflow_dispatch:
 
 jobs:
-
   build:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest]
-        go: [1.16, 1.17]
+        go: [1.18.x, 1.21.x]
     steps:
       - uses: actions/checkout@v2
 
       - name: Set up Go
         uses: actions/setup-go@v2
+        run: |
+          go mod download
         with:
           go-version: ${{ matrix.go }}