[gnome-continuous] Bump up the version of Meson

[Emmanuele Bassi <ebassi src gnome org>]

commit c102f7db6c48eb85921f78fbe4fc42ead83e3e0f
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Fri Aug 16 15:15:59 2019 +0100

    Bump up the version of Meson

 manifest.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/manifest.json b/manifest.json
index 839915c..478b0e6 100644
--- a/manifest.json
+++ b/manifest.json
@@ -68,7 +68,7 @@
 
                 {"src": "git:https://github.com/mesonbuild/meson.git";,
                  "name": "meson",
-                 "tag": "0.50.1",
+                 "tag": "0.51.1",
                  "component": "devel",
                  "patches": ["python-meson-buildsys.patch"]},