[AppVeyor] Deploy artifacts to GitHub Releases.

[AppVeyor] Deploy artifacts to GitHub Releases, take four.

I guess before_deploy is broken?

.appveyor.yml

@@ -25,6 +25,12 @@ pull_requests:
 
 os: Visual Studio 2019
 
+init:
+  - ps: |
+      If (-Not $env:APPVEYOR_PULL_REQUEST_NUMBER) {
+        $env:is_not_pr = "true"
+      }
+
 install:
   - |
     vcpkg integrate remove
@@ -56,12 +62,6 @@ artifacts:
   - path: '*.zip'
   - path: xenia-cpu-ppc-test.log
 
-before_deploy:
-  - ps: |
-      If (-Not $env:APPVEYOR_PULL_REQUEST_NUMBER) {
-        $env:is_not_pr = "true"
-      }
-
 deploy:
   - provider: Environment
     name: xenia-master