ci: disable a test on github-action

It seems that the CI environment kill non authenticated requests

bridge/github/config_test.go

@@ -104,6 +104,10 @@ func TestValidateUsername(t *testing.T) {
 		t.Skip("Travis environment: avoiding non authenticated requests")
 	}
 
+	if _, has := os.LookupEnv("CI"); has {
+		t.Skip("Github action environment: avoiding non authenticated requests")
+	}
+
 	tests := []struct {
 		name  string
 		input string