fix: Update proguard / R8 consumer rules for Retrofix et-al#76

gazreese wants to merge 1 commit intoFlagsmith:mainFlagsmith/flagsmith-kotlin-android-client:mainfrom

foresightmobile:fix/add-proguard-rules-retrofitforesightmobile/flagsmith-kotlin-android-client:fix/add-proguard-rules-retrofitCopy head branch name to clipboard