change go version

Author: moutonjeremy

.github/workflows/release.yml

@@ -12,9 +12,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@master
-      - uses: actions/setup-go@v1
+      - uses: actions/setup-go@v2
         with:
-          go-version: '1.13.5'
+          go-version: '1.15'
 
       - name: Build
         run: CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o github-actions-exporter