use v3 feed in integration test suite

Author: matthid

integrationtests/core-context-exists/before/context.exists.fsx

@@ -1,7 +1,7 @@
 #if FAKE_DEPENDENCIES
 #r "paket:
 storage: none
-source https://nuget.org/api/v2
+source https://api.nuget.org/v3/index.json
 source ../../../release/dotnetcore
 //source https://ci.appveyor.com/nuget/paket
 

integrationtests/core-reference-fake-core-targets/before/reference_fake-targets.fsx

@@ -1,6 +1,6 @@
 #if FAKE_DEPENDENCIES
 #r "paket:
-source https://nuget.org/api/v2
+source https://api.nuget.org/v3/index.json
 source ../../../release/dotnetcore
 
 nuget Fake.Core.Target prerelease

integrationtests/core-reference-fake-runtime/before/reference_fake-runtime.fsx

@@ -1,7 +1,7 @@
 #if FAKE_DEPENDENCIES
 #r "paket:
 storage: none
-source https://nuget.org/api/v2
+source https://api.nuget.org/v3/index.json
 source ../../../release/dotnetcore
 //source https://ci.appveyor.com/nuget/paket
 

integrationtests/core-simple-failed-to-compile/before/fail-to-compile.fsx

@@ -1,6 +1,6 @@
 #if FAKE_DEPENDENCIES
 #r "paket:
-source https://nuget.org/api/v2
+source https://api.nuget.org/v3/index.json
 source ../../../release/dotnetcore
 //source https://ci.appveyor.com/nuget/paket
 

integrationtests/core-simple-runtime-error/before/runtime-error.fsx

@@ -1,6 +1,6 @@
 #if FAKE_DEPENDENCIES
 #r "paket: storage: none"
-#r "paket: source https://nuget.org/api/v2"
+#r "paket: source https://api.nuget.org/v3/index.json"
 #r "paket: source ../../../release/dotnetcore"
 #r "paket: //source https://ci.appveyor.com/nuget/paket"
 #r "paket: nuget Fake.Runtime prerelease"