patch 9.1.0725: filetype: swiftinterface files are not recognized

Problem:  filetype: swiftinterface files are not recognized
Solution: Detect '*.swiftinterface' files as swift filetype
          (LosFarmosCTL)

closes: #15658

Signed-off-by: LosFarmosCTL <80157503+LosFarmosCTL@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/filetype.vim

@@ -2371,7 +2371,7 @@ au BufNewFile,BufRead *.sml			setf sml
 au BufNewFile,BufRead *.cm			setf voscm
 
 " Swift
-au BufNewFile,BufRead *.swift			setf swift
+au BufNewFile,BufRead *.swift,*.swiftinterface	setf swift
 au BufNewFile,BufRead *.swift.gyb		setf swiftgyb
 
 " Swift Intermediate Language or SILE

src/testdir/test_filetype.vim

@@ -712,7 +712,7 @@ def s:GetFilenameChecks(): dict<list<string>>
     svg: ['file.svg'],
     svn: ['svn-commitfile.tmp', 'svn-commit-file.tmp', 'svn-commit.tmp'],
     swayconfig: ['/home/user/.sway/config', '/home/user/.config/sway/config', '/etc/sway/config', '/etc/xdg/sway/config'],
-    swift: ['file.swift'],
+    swift: ['file.swift', 'file.swiftinterface'],
     swiftgyb: ['file.swift.gyb'],
     swig: ['file.swg', 'file.swig'],
     sysctl: ['/etc/sysctl.conf', '/etc/sysctl.d/file.conf', 'any/etc/sysctl.conf', 'any/etc/sysctl.d/file.conf'],

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    725,
 /**/
     724,
 /**/