Change ci.bazel.io status badges to use https.

RELNOTES: None.
PiperOrigin-RevId: 172771645
diff --git a/README.md b/README.md
index 812a542..4038669 100644
--- a/README.md
+++ b/README.md
@@ -45,7 +45,7 @@
 
 See [CONTRIBUTING.md](CONTRIBUTING.md)
 
-[![Build Status](http://ci.bazel.io/buildStatus/icon?job=bazel-tests)](http://ci.bazel.io/job/bazel-tests)
+[![Build Status](https://ci.bazel.io/buildStatus/icon?job=bazel-tests)](https://ci.bazel.io/job/bazel-tests)
 
 Bazel is released in 'Beta'.
 See the [product roadmap](https://bazel.build/roadmap.html) to learn about the