Use 'group: stable' in Travis config.

Comparing with previous successful build with xcode11.3 at #4149, this setting is missing now.
DynamoRIO · Jul 1, 2020 · 5a2056e · 5a2056e
1 parent f3b896b
commit 5a2056e
Showing 1 changed file with 1 addition and 0 deletions.
diff --git a/.travis.yml b/.travis.yml
@@ -47,6 +47,7 @@ branches:
 sudo: required
 dist: xenial
 osx_image: xcode11.3
+group: stable
 
 language:
   - c