iOS 11+ ARCH set to ARCHS_STANDARD

[zulkis]

Describe the bug

After pod install While building project for iOS 11+ I am getting:

Pods/RxBluetoothKit/Source/CBCentralManagerDelegateWrapper.swift:3:8: could not find module 'RxSwift' for target 'armv7-apple-ios'; found: arm64, arm64-apple-ios

Expected behavior
Build is successful, no compilation issues.
Since RxBluetoothKit having RxSwift as a dependency, I think it should behave same way as RxCocoa, which does not have this issue.

Environment:
Xcode 11.5
Fastlane 2.137.0
Cocoapods 1.8.4

Podfile:

platform :ios, '11.0'
...
pod 'RxSwift',  '~> 5.1.1'
pod 'RxBluetoothKit', '~> 5.3'

I've found quick fix on Podfile level, still it is just temporary:

post_install do |installer|
    installer.pods_project.targets.each do |target|
        if target.name == 'RxBluetoothKit'
            target.build_configurations.each do |config|
                config.build_settings['ARCHS'] = '$(ARCHS_STANDARD_64_BIT)'
            end
        end
    end
end