Bump Go version to 1.21 in build workflow

Author: robertmu

.github/workflows/build_and_unit_test.yml

@@ -21,7 +21,7 @@ jobs:
     - name: Set up Go
       uses: actions/setup-go@v2
       with:
-        go-version: 1.17
+        go-version: 1.21
 
     - name: Set Environment
       run: |