reflect the wangle github branch rename from master to main

Summary:
The primary branch in the GitHub wangle repository has been renamed from
`master` to `main`.  Update the getdeps manifest to reflect this, so that
getdeps builds correctly clone the repository.

Reviewed By: xavierd

Differential Revision: D30822418

fbshipit-source-id: 9670fff1e85e77adf84485ff8f2236f8826630ef

build/fbcode_builder/manifests/wangle

@@ -6,6 +6,7 @@ shipit_fbcode_builder = true
 
 [git]
 repo_url = https://github.com/facebook/wangle.git
+rev = main
 
 [build]
 builder = cmake