Add empty test api version header checker

Signed-off-by: Asai Neko <sugar@sne.moe>

middleware/api_version.go

@@ -0,0 +1,14 @@
+package middleware
+
+import "github.com/gin-gonic/gin"
+
+func ApiVersionCheck() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		apiVersion := c.GetHeader("X-Api-Version")
+		if apiVersion == "" {
+			c.Abort()
+			return
+		}
+		c.Next()
+	}
+}