Use standardized command in go:build task

This is the command used in the standardized "template" task that should be used in all Go projects.

The previous `GO_BUILD_FLAGS` variable was intended to allow the developer to specify arbitrary arguments via the command
line, but that is not needed.

The `LDFLAGS` variable that is introduced here allows injecting data to the build, which is used in more complex
applications, but not in this one at the moment.

Author: per1234

Taskfile.yml

@@ -26,7 +26,7 @@ tasks:
   go:build:
     desc: Build the Go code
     cmds:
-      - go build -v {{.GO_BUILD_FLAGS}}
+      - go build -v {{.LDFLAGS}}
 
   # Source: https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/assets/test-go-task/Taskfile.yml
   go:test: