fix: infer MiniMax vendor for MiniMax models (#6164)

* fix: infer MiniMax vendor for MiniMax models

* Delete model/pricing_default_test.go

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Co-authored-by: duanxufu <duanxufu@rededa.com>

model/pricing_default.go

@@ -20,6 +20,7 @@ var defaultVendorRules = map[string]string{
 	"qwen":     "阿里巴巴",
 	"deepseek": "DeepSeek",
 	"abab":     "MiniMax",
+	"minimax":  "MiniMax",
 	"ernie":    "百度",
 	"spark":    "讯飞",
 	"hunyuan":  "腾讯",