Exclude stable and old SDK on travis

pkgs/stream_transform/.travis.yml

diff --git a/pkgs/stream_transform/.travis.yml b/pkgs/stream_transform/.travis.yml
index 57bec94..65c7fc3 100644
--- a/pkgs/stream_transform/.travis.yml
+++ b/pkgs/stream_transform/.travis.yml
@@ -2,8 +2,6 @@
 sudo: false
 dart:
   - dev
-  - stable
-  - 1.22.1
 cache:
   directories:
     - $HOME/.pub-cache
@@ -14,9 +12,3 @@
   - dartfmt
   - dartanalyzer
   - dartanalyzer: --no-strong .
-matrix:
-  exclude:
-    - dart: 1.22.1
-      dart_task: dartfmt
-    - dart: 1.22.1
-      dart_task: dartanalyzer