Fix event entry download

Event entry should be downloaded with specific http header of "Accept:
application/octet-stream" or "*/*", but the default http header is set
to "Accept: application/json", so need to specify the header for event
downloading.

Refer: https://gerrit.openbmc.org/c/openbmc/bmcweb/+/40136

Tested:
Event entry data can be downloaded with the fix.

Change-Id: Ia45123340da79a54fc4229470e6822206b8df808
Signed-off-by: Sean Zhang <xiazhang@nvidia.com>

src/store/modules/Logs/EventLogStore.js

@@ -222,7 +222,11 @@ const EventLogStore = {
     },
     async downloadEntry(_, uri) {
       return await api
-        .get(uri)
+        .get(uri, {
+          headers: {
+            Accept: 'application/octet-stream',
+          },
+        })
         .then((response) => {
           const blob = new Blob([response.data], {
             type: response.headers['content-type'],