[Bug] 🐛 部分 RSS 客户端要求需要 content-type 请求头

[PBK-B]

Bug 描述
部分 RSS 客户端需要正确的 content-type: application/rss+xml 响应头，如 https://github.com/FreshRSS/FreshRSS

复现步骤

$ curl -I https://bin.zmide.com/?feed=rss2
HTTP/2 200 
server: nginx
date: Thu, 13 Jun 2024 03:57:02 GMT
content-type: application/rss+xml; charset=UTF-8
last-modified: Fri, 07 Jun 2024 13:42:31 GMT
etag: "a1e9a6ed990a9be2dfee53c813b18255"
strict-transport-security: max-age=31536000

$ curl -I https://direct.xeu.life/sub/rss.xml
HTTP/2 404 
date: Thu, 13 Jun 2024 03:57:45 GMT
content-type: text/plain;charset=UTF-8
access-control-allow-origin: *
vary: *
access-control-allow-headers: Authorization, content-type
access-control-allow-methods: *
access-control-expose-headers: *
cf-placement: local-LHR
server: cloudflare
cf-ray: 89xxxxxx1417f-LHR
alt-svc: h3=":443"; ma=86400

期望行为
部分 RSS 客户端需要正确的 content-type: application/rss+xml; charset=UTF-8 响应头

截图
nil

环境变量
nil