Add GitHub CI test workflows

Change-Id: Ie8d258356a4975922fe102f6b18ec3289d753bed
diff --git a/.gitignore b/.gitignore
index ffce448..b176bc7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -29,6 +29,7 @@
 *.cache
 .*
 !.gitignore
+!.github
 
 # Protected checks
 t/corpus/BRZ13