patch 9.0.0711: SubStation Alpha files are not recognized

Problem:    SubStation Alpha files are not recognized.
Solution:   Add patterns for SubStation Alpha files. (closes #11332)
diff --git a/src/testdir/test_filetype.vim b/src/testdir/test_filetype.vim
index ba18b85..0449bfd 100644
--- a/src/testdir/test_filetype.vim
+++ b/src/testdir/test_filetype.vim
@@ -536,6 +536,7 @@
     \ 'squirrel': ['file.nut'],
     \ 'srec': ['file.s19', 'file.s28', 'file.s37', 'file.mot', 'file.srec'],
     \ 'srt': ['file.srt'],
+    \ 'ssa': ['file.ass', 'file.ssa'],
     \ 'sshconfig': ['ssh_config', '/.ssh/config', '/etc/ssh/ssh_config.d/file.conf', 'any/etc/ssh/ssh_config.d/file.conf', 'any/.ssh/config', 'any/.ssh/file.conf'],
     \ 'sshdconfig': ['sshd_config', '/etc/ssh/sshd_config.d/file.conf', 'any/etc/ssh/sshd_config.d/file.conf'],
     \ 'st': ['file.st'],
diff --git a/src/version.c b/src/version.c
index 2b922f3..d3189fb 100644
--- a/src/version.c
+++ b/src/version.c
@@ -700,6 +700,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    711,
+/**/
     710,
 /**/
     709,