Avoid using Cocoapods 1.15 until it fixes an issue affection RN. (#42702)

Summary:
Cocoapods 1.15 (https://github.com/facebook/react-native/issues/42698) current breaks the build, limit to version >= 1.13 & < 1.15

This is currently broken and affecting users, we'll remove this limit once Cocopods fixes the regression.  It's currently blocking 0.73.3.

## Changelog:
[iOS][Fixed] don't allow cocoapods 1.15.

packages/react-native/template/Gemfile

@@ -3,5 +3,7 @@ source 'https://rubygems.org'
 # You may use http://rbenv.org/ or https://rvm.io/ to install and use this version
 ruby ">= 2.6.10"
 
-gem 'cocoapods', '~> 1.13'
+# Cocoapods 1.15 introduced a bug which break the build. We will remove the upper
+# bound in the template on Cocoapods with next React Native release.
+gem 'cocoapods', '>= 1.13', '< 1.15'
 gem 'activesupport', '>= 6.1.7.3', '< 7.1.0'

packages/rn-tester/Gemfile

@@ -1,6 +1,8 @@
 # Gemfile
 source 'https://rubygems.org'
 
-gem 'cocoapods', '~> 1.12'
+# Cocoapods 1.15 introduced a bug which break the build. We will remove the upper
+# bound in the template on Cocoapods with next React Native release.
+gem 'cocoapods', '>= 1.13', '< 1.15'
 gem 'rexml'
 gem 'activesupport', '>= 6.1.7.3', '< 7.1.0'