refactor: use runtime.Version() instead of hardcoded goVersion

Replaced hardcoded goVersion constant with parseGoVersion() function
that dynamically extracts the Go version from runtime.Version().
This eliminates the need to update the version manually.

🤖 Generated with [codeagent](https://github.com/qbox/codeagent)
Co-authored-by: luoliwoshang <luoliwoshang@users.noreply.github.com>

runtime/internal/lib/go/build/build.go

@@ -13,13 +13,32 @@ import (
 	"path/filepath"
 	"runtime"
 	"strconv"
+	"strings"
 )
 
 // Type aliases to reference standard library types
 type Context = build.Context
 
-// Go version constant (Go 1.24)
+// parseGoVersion extracts the minor version number from runtime.Version()
-const goVersion = 24
+// e.g., "go1.24" or "go1.24.1" -> 24
+func parseGoVersion() int {
+	v := runtime.Version()
+	// Strip "go" prefix
+	if strings.HasPrefix(v, "go") {
+		v = v[2:]
+	}
+	// Extract version like "1.24" or "1.24.1"
+	parts := strings.Split(v, ".")
+	if len(parts) >= 2 {
+		if minor, err := strconv.Atoi(parts[1]); err == nil {
+			return minor
+		}
+	}
+	// Fallback to a reasonable default if parsing fails
+	return 24
+}
+
+var goVersion = parseGoVersion()
 
 var defaultToolTags []string
 var defaultReleaseTags []string