ci: fix the environment variable settings in the testing workflow

Author: lvan100

.github/workflows/test.yml

@@ -24,7 +24,8 @@ jobs:
         run: go mod download
 
       - name: Run tests
-        run: go test -count=1 -coverprofile=coverage.txt ./... &&
+        run: export =::=:: &&
+          go test -count=1 -coverprofile=coverage.txt ./... &&
           grep -v "^github.com/go-spring/spring-core/gs/examples" coverage.txt > coverage.txt.tmp && mv coverage.txt.tmp coverage.txt
 
       - name: Upload results to Codecov