error: SWIFT_VERSION '3.0' is unsupported when running ./bootstrap.sh

Hello!
After running
```
brew update
brew bundle --file="homebrew/Brewfile"
brew upgrade usbmuxd libimobiledevice --fetch-HEAD
```
I run
./bootstrap.sh
and get error about unsupported swift version.
How I can fix it?
```Last login: Fri Nov 29 11:06:11 on ttys001
Ilyas-MacBook-Pro:ios-device-server-master ilyamakarevich$ ./bootstrap.sh
Building fbsimctl...
/var/folders/t7/typpx7mn1lxdt8kd5p2pr9zc0000gn/T/tmp.aUygFi2R ~/ios-device-server-master
Checking out https://github.com/facebook/FBSimulatorControl.git#ec54965 at /var/folders/t7/typpx7mn1lxdt8kd5p2pr9zc0000gn/T/tmp.aUygFi2R
Cloning into '/var/folders/t7/typpx7mn1lxdt8kd5p2pr9zc0000gn/T/tmp.aUygFi2R'...
remote: Enumerating objects: 1065, done.
remote: Counting objects: 100% (1065/1065), done.
remote: Compressing objects: 100% (947/947), done.
remote: Total 39394 (delta 224), reused 378 (delta 110), pack-reused 38329
Receiving objects: 100% (39394/39394), 88.24 MiB | 8.57 MiB/s, done.
Resolving deltas: 100% (29739/29739), done.
Note: checking out 'ec54965'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -b with the checkout command again. Example:

git checkout -b

HEAD is now at ec54965b remove deprecated .characters
Building fbsimctl to /var/folders/t7/typpx7mn1lxdt8kd5p2pr9zc0000gn/T/tmp.aUygFi2R/build
using target fbsimctl
using command build
using output directory /var/folders/t7/typpx7mn1lxdt8kd5p2pr9zc0000gn/T/tmp.aUygFi2R/build
/usr/local/bin/carthage
/var/folders/t7/typpx7mn1lxdt8kd5p2pr9zc0000gn/T/tmp.aUygFi2R/fbsimctl /var/folders/t7/typpx7mn1lxdt8kd5p2pr9zc0000gn/T/tmp.aUygFi2R
Please update to the latest Carthage version: 0.34.0. You currently are on 0.33.0
*** Checking out GCDWebServer at "3.3.3"
*** xcodebuild output can be found in /var/folders/t7/typpx7mn1lxdt8kd5p2pr9zc0000gn/T/carthage-xcodebuild.qflx6s.log
*** Building scheme "GCDWebServers (Mac)" in GCDWebServer.xcodeproj
/var/folders/t7/typpx7mn1lxdt8kd5p2pr9zc0000gn/T/tmp.aUygFi2R

❌ error: SWIFT_VERSION '3.0' is unsupported, supported versions are: 4.0, 4.2, 5.0. (in target 'FBSimulatorControlKit' from project 'fbsimctl')

** BUILD FAILED **

Ilyas-MacBook-Pro:ios-device-server-master ilyamakarevich$
```

Thanks!

Start with bootstrap.sh and the FBSimulatorControl checkout used to build fbsimctl, then inspect the Carthage xcodebuild log for the FBSimulatorControlKit target. Compare the checked-out dependency and available Swift versions to determine the compatibility change needed; done means ./bootstrap.sh completes without the unsupported SWIFT_VERSION error.

Written by the indexing model from the issue text.