Add syntax & ftplugin for pymanifest (#12773)

diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
index 21d57a6..911de1e 100644
--- a/.github/CODEOWNERS
+++ b/.github/CODEOWNERS
@@ -189,6 +189,7 @@
 runtime/ftplugin/postscr.vim		@mrdubya
 runtime/ftplugin/ps1.vim		@heaths
 runtime/ftplugin/ps1xml.vim		@heaths
+runtime/ftplugin/pymanifest.vim		@ObserverOfTime
 runtime/ftplugin/python.vim		@tpict
 runtime/ftplugin/qb64.vim		@dkearns
 runtime/ftplugin/r.vim			@jalvesaq
@@ -439,6 +440,7 @@
 runtime/syntax/ps1.vim			@heaths
 runtime/syntax/ps1xml.vim		@heaths
 runtime/syntax/psl.vim			@danielkho
+runtime/syntax/pymanifest.vim		@ObserverOfTime
 runtime/syntax/qb64.vim			@dkearns
 runtime/syntax/r.vim			@jalvesaq
 runtime/syntax/racket.vim		@benknoble