talksapp: use https for the compile url

Fixes golang/gddo#418

Change-Id: I8ec374a74765d751a714dcf61c7caec534c8333d
Reviewed-on: https://go-review.googlesource.com/26653
Reviewed-by: Chris Broadfoot <cbro@golang.org>
diff --git a/talksapp/main.go b/talksapp/main.go
index 029caef..fa58533 100644
--- a/talksapp/main.go
+++ b/talksapp/main.go
@@ -38,7 +38,7 @@
 
 	// used for mocking in tests
 	getPresentation = gosrc.GetPresentation
-	playCompileURL  = "http://play.golang.org/compile"
+	playCompileURL  = "https://play.golang.org/compile"
 )
 
 func init() {