[gnome-continuous] Revert "Bump up the version of Meson"

[Emmanuele Bassi <ebassi src gnome org>]

commit 64deb2808cc8cbbfcc03f8a705a65ec56a71b673
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Sat Aug 17 15:16:34 2019 +0100

    Revert "Bump up the version of Meson"
    
    This reverts commit c102f7db6c48eb85921f78fbe4fc42ead83e3e0f.
    
    Seems something breaks in Continuous when updating Meson.

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