fix linting errors: unused var t, unexported-return

```
runner/util_test.go:237:34: unused-parameter: parameter 't' seems to be unused, consider removing or renaming it as _ (revive)
func TestGetStructureFieldTagMap(t *testing.T) {
```

```
main.go:54:1: exported function GetVersionInfo should have comment or be unexported
main.go:54:23: exported func GetVersionInfo returns unexported type main.versionInfo, which can be annoying to use
```

main.go

@@ -51,7 +51,7 @@ type versionInfo struct {
 	goVersion  string
 }
 
-func GetVersionInfo() versionInfo {
+func GetVersionInfo() versionInfo { //revive:disable:unexported-return
 	if len(airVersion) != 0 && len(goVersion) != 0 {
 		return versionInfo{
 			airVersion: airVersion,

runner/util_test.go

@@ -237,6 +237,7 @@ func Test_killCmd_SendInterrupt_false(t *testing.T) {
 func TestGetStructureFieldTagMap(t *testing.T) {
 	c := Config{}
 	tagMap := flatConfig(c)
+	assert.NotEmpty(t, tagMap)
 	for _, i2 := range tagMap {
 		fmt.Printf("%v\n", i2.fieldPath)
 	}