update versions in the build workflow (#9)

Author: reugn

.github/workflows/build.yml

@@ -13,10 +13,10 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go-version: [1.19.x]
+        go-version: [1.18.x, 1.20.x]
     steps:
     - name: Setup Go
-      uses: actions/setup-go@v3
+      uses: actions/setup-go@v4
       with:
         go-version: ${{ matrix.go-version }}
 
@@ -27,4 +27,5 @@ jobs:
       run: go test . -coverprofile=coverage.out -covermode=atomic
 
     - name: Upload coverage to Codecov
+      if: ${{ matrix.go-version == '1.18.x' }}
       run: bash <(curl -s https://codecov.io/bash)