set image size for open graph

src/components/Base.astro

···
           />
           <meta property="og:type" content={graph.type ?? "website"} />
           <meta property="og:image" content={banner} />
+          <meta property="og:image:width" content="600" />
+          <meta property="og:image:height" content="400" />
         </Fragment>
       )
     }