Change deploy to branch release/v4

v4 has an open pull request and so it is skipped (to avoid duplicate builds for PRs),
but now that we want to deploy we simply create a new branch release/v4 and
merge into it whenever we want to deploy v4 branch.

Author: angularsen

appveyor.yml

@@ -1,7 +1,7 @@
 version: '{build}'
 image: Visual Studio 2017
 skip_commits:
-  files:
+ files:
    - docs/*
    - '**/*.md'
 
@@ -61,4 +61,4 @@ deploy:
     secure: NlJ+D6kXfgU6RgRuf9okylLDENp8DA3tTRSC6UHBNbRS9ZAvRrC3Z0++Mr5VtGvz
   skip_symbols: false
   on:
-    branch: v4
+    branch: release/v4