[gnome-subtitles/meson-port] Require gstreamer 1.18

[Pedro Castro <pcastro src gnome org>]

commit bfd2b67ee4b4ad576bd851185b0c644709bdbd77
Author: Pedro Castro <pedro gnomesubtitles org>
Date:   Fri Jun 3 08:40:28 2022 +0100

    Require gstreamer 1.18

 subprojects/gstreamer-sharp.wrap | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/subprojects/gstreamer-sharp.wrap b/subprojects/gstreamer-sharp.wrap
index 76ddab2..7018cbb 100644
--- a/subprojects/gstreamer-sharp.wrap
+++ b/subprojects/gstreamer-sharp.wrap
@@ -1,4 +1,4 @@
 [wrap-git]
 directory=gstreamer-sharp
 url=https://gitlab.freedesktop.org/gstreamer/gstreamer-sharp.git
-revision=tags/1.18.5
+revision=tags/1.18.0