[gnome-build-meta/sam/vala-0.48.7] Pin vala to 0.48.7

[Sam Thursfield <sthursfield src gnome org>]

commit 7606c8cf469b95b366aac44a227f56531be66cfb
Author: Sam Thursfield <sam afuera me uk>
Date:   Mon Aug 10 12:50:45 2020 +0200

    Pin vala to 0.48.7
    
    See https://gitlab.gnome.org/GNOME/gnome-build-meta/-/issues/307

 elements/sdk/vala.bst | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
---
diff --git a/elements/sdk/vala.bst b/elements/sdk/vala.bst
index b6f27cb0..595fca09 100644
--- a/elements/sdk/vala.bst
+++ b/elements/sdk/vala.bst
@@ -2,7 +2,10 @@ kind: autotools
 sources:
 - kind: git_tag
   url: gitlab_gnome_org:GNOME/vala.git
-  track: master
+
+  # Pinned to 0.48,7, see:
+  # https://gitlab.gnome.org/GNOME/gnome-build-meta/-/issues/307
+  track: 0.48.7
 build-depends:
 - sdk/vala-tarball.bst
 - freedesktop-sdk.bst:components/bison.bst