bump go

Author: teaguru

.github/workflows/build_test.yml

@@ -16,7 +16,7 @@ jobs:
         name: set up Go
         uses: actions/setup-go@v1
         with:
-          go-version: 1.15.x
+          go-version: 1.21.x
       -
         name: cache modules
         uses: actions/cache@v2