Add self to maintainers (#23644)

Hi all,

I've very much enjoyed working on Gitea and was hoping to make it
official by requesting maintainership. :) Excited to see what the future
holds for this project.

My [merged PRs
list](https://github.com/go-gitea/gitea/pulls?q=is%3Apr+author%3Aphilip-peterson+is%3Amerged+)

Cheers,
Phil

---------

Co-authored-by: John Olheiser <john.olheiser@gmail.com>

Author: philip-peterson

MAINTAINERS

@@ -51,3 +51,4 @@ Dong Ge <gedong_1994@163.com> (@sillyguodong)
 Xinyi Gong <hestergong@gmail.com> (@HesterG)
 wxiaoguang <wxiaoguang@gmail.com> (@wxiaoguang)
 Gary Moon <gary@garymoon.net> (@garymoon)
+Philip Peterson <philip.c.peterson@gmail.com> (@philip-peterson)