Use --synchronous option for pushing FlipperKit cocoapod which should fix consistency issue

Summary: This is suggested as a fix for the consistency issue (https://github.com/facebook/flipper/issues/1638) when interdependent packages published together and one of them cannot find another because it takes time to synchronise published packages to CDN. This fix is suggested here: https://github.com/CocoaPods/CocoaPods/issues/9497.

Reviewed By: mweststrate

Differential Revision: D25184732

fbshipit-source-id: d8d58b33f65ff7e87f935fb7cb85964dbf95dd13

.github/workflows/publish-pods.yml

@@ -43,7 +43,7 @@ jobs:
       - name: Push FlipperKit
         run: |
           # Retry publishing FlipperKit 20 times. Putting this hack unless we have cocoapods 1.10. More information related to the bug https://github.com/CocoaPods/CocoaPods/issues/9502#issuecomment-579486258
-          for i in {1..20}; do pod trunk push FlipperKit.podspec --use-libraries --allow-warnings --verbose --skip-import-validation && break || sleep 30; done
+          for i in {1..20}; do pod trunk push FlipperKit.podspec --use-libraries --allow-warnings --verbose --skip-import-validation --synchronous && break || sleep 30; done
         env:
           COCOAPODS_TRUNK_TOKEN: ${{ secrets.COCOAPODS_TRUNK_TOKEN }}