[iOS] Bump up the Cocoapods version (pytorch#53335)

Summary:
Pull Request resolved: pytorch#53335

ghstack-source-id: 123166245

(Note: this ignores all push blocking failures!)

Test Plan: CI

Reviewed By: xta0

Differential Revision: D26838693

fbshipit-source-id: 0007eba40b3145c8ba77b3211759f0609e17f561

ios/LibTorch.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
     s.name             = 'LibTorch'
-    s.version          = '1.7.1'
+    s.version          = '1.8.0'
     s.authors          = 'PyTorch Team'
     s.license          = { :type => 'BSD' }
     s.homepage         = 'https://github.com/pytorch/pytorch'