fix: serve svg+xml as svg (#13277)

Based from https://github.com/payloadcms/payload/pull/13276

Fixes https://github.com/payloadcms/payload/issues/7624

If an uploaded image has `.svg` ext, and the mimeType is read as
`application/xml` adjust the mimeType to `image/svg+xml`.

---------

Co-authored-by: Philipp Schneider <47689073+philipp-tailor@users.noreply.github.com>

packages/payload/src/uploads/endpoints/getFile.ts

@@ -93,9 +93,14 @@ export const getFileHandler: PayloadHandler = async (req) => {
 
   const data = streamFile(filePath)
   const fileTypeResult = (await fileTypeFromFile(filePath)) || getFileTypeFallback(filePath)
+  let mimeType = fileTypeResult.mime
+
+  if (filePath.endsWith('.svg') && fileTypeResult.mime === 'application/xml') {
+    mimeType = 'image/svg+xml'
+  }
 
   let headers = new Headers()
-  headers.set('Content-Type', fileTypeResult.mime)
+  headers.set('Content-Type', mimeType)
   headers.set('Content-Length', stats.size + '')
   headers = collection.config.upload?.modifyResponseHeaders
     ? collection.config.upload.modifyResponseHeaders({ headers }) || headers