Update for Xcode 12

Version 7.0 (#242)

Fix clipping value knob (#219)

* fix clipping of value knob

* update changelog and docs

add swift package manager support, update gems

update pod spec and changelog

update changelog and podspec to 6.2.1

v6.2.0 (#196)

add ability to start timer from some other time

closes #184

Version 6.1.0 (#182)

Merge branch 'master' of github.com:luispadron/UICircularProgressRing

add new archive script