Merge PR #6026: Backport "Merge PR #6025: CI(appveyor): Use release signing"

Author: Krzmbrzl

.appveyor.yml

@@ -43,6 +43,6 @@ artifacts:
 
 deploy:
   - provider: Webhook
-    url: https://app.signpath.io/API/v1/79916aba-7a9f-448d-91c6-fb83593b59d3/Integrations/AppVeyor?ProjectSlug=mumble&SigningPolicySlug=test-signing
+    url: https://app.signpath.io/API/v1/79916aba-7a9f-448d-91c6-fb83593b59d3/Integrations/AppVeyor?ProjectSlug=mumble&SigningPolicySlug=release-signing
     authorization:
       secure: WKbGSfFSHTtODf6eHRSHPAobctJli48O/VoMpCYTuIlITl2piOpCH6igCRDX4EuJTzgDX45H34tVfPuNzSMdLA==