Update travis to use xcode12

Merge pull request LoopKit#1397 from LoopKit/dev

Release 2.2.4

Merge pull request LoopKit#1390 from LoopKit/dev

Release 2.2.3

Bump version

Fix release version

Merge pull request LoopKit#1305 from LoopKit/dev

Release 2.2

Bump xcconfig version

G6 hotfix (LoopKit#1014)

* Update carthage to use g6 hotfix

* Bump version for hotfix release

* Use CGMBLEKit v3.1

updates for Xcode 10.2 (LoopKit#910)

* updates for Xcode 10.2

* Use swift charts 0.6.3 with xcode 10.2 patch

* bump version for hotfix

Merge pull request LoopKit#868 from LoopKit/dev

Release 1.9.4