fix: "Multiple Podfiles were found" due to vendor inclusion

[robhogan]

Summary:

cli-plugin-ios performs a glob search for Podfile as a heuristic for the ios project root. In a default installation, where Bundler installs Cocoapods as a gem into vendor, the vendored cocoapods directory itself contains a Podfile, and this leads to a harmless but noisy warning:

warn Multiple Podfiles were found: ios/Podfile,vendor/bundle/ruby/2.7.0/gems/cocoapods-core-1.12.1/lib/cocoapods-core/Podfile. Choosing ios/Podfile automatically. If you would like to select a different one, you can configure it via "project.ios.sourceDir". You can learn more about it here: https://github.com/react-native-community/cli/blob/master/docs/configuration.md

This amends the existing exclusion list for the Podfile search (which already hardcodes and exclusion for eg /node_modules/ to also exclude Bundler's equivalent, /vendor/.

Test Plan:

Made this change locally (I happen to be working in RN 0.71.11 but I don't think anything relevant has changed here)

Before

After

[thymikee]

Thank you!