Specify Swift 4.2 in podspecs (#297)

* Bumped PiwikTracker podspec to Swift 4.2

* Specified Swift 4.2 in MatomoTracker podspec

* Bump CHANGELOG.md with podspec update mention

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Unreleased
 * **improvement** Made copyFromOldSharedInstance available from Objective-C. [#282] (https://github.com/matomo-org/matomo-sdk-ios/issues/282)
 * **improvement** Accepting urls ending in `matomo.php` in addition to `piwik.php` when initializing a new instance. [#286] (https://github.com/matomo-org/matomo-sdk-ios/pull/286)
+* **bugfix**  Specified Swift 4.2 in both `.podspec` files. [#297] (https://github.com/matomo-org/matomo-sdk-ios/pull/297)
 
 ## 6.0.0
 * **feature** Added the possibility to implement custom queues. [#137](https://github.com/matomo-org/matomo-sdk-ios/issues/137)

MatomoTracker.podspec

@@ -11,6 +11,7 @@ Pod::Spec.new do |spec|
   spec.osx.deployment_target = '10.12'
   spec.requires_arc = true
   spec.default_subspecs = 'Core'
+  spec.swift_version = '4.2'
 
   spec.subspec 'Core' do |core|
   	core.source_files = 'MatomoTracker/*.swift'

PiwikTracker.podspec

@@ -11,7 +11,7 @@ Pod::Spec.new do |spec|
   spec.osx.deployment_target = '10.12'
   spec.requires_arc = true
   spec.default_subspecs = 'Core'
-  spec.swift_version = '4.1'
+  spec.swift_version = '4.2'
 
   spec.deprecated_in_favor_of = 'MatomoTracker'