feat: initial Go project with test

go.mod

@@ -0,0 +1,3 @@
+module test-go-project
+
+go 1.22

main.go

@@ -0,0 +1,11 @@
+package main
+
+import "fmt"
+
+func main() {
+	fmt.Println("Hello from Forgejo!")
+}
+
+func Add(a, b int) int {
+	return a + b
+}

main_test.go

@@ -0,0 +1,9 @@
+package main
+
+import "testing"
+
+func TestAdd(t *testing.T) {
+	if got := Add(2, 3); got != 5 {
+		t.Errorf("Add(2, 3) = %d, want 5", got)
+	}
+}