Update README for 1.2.0 (#177)

Author: mbrandonw

README.md

@@ -131,7 +131,7 @@ If your data can be represented as an image, text, or data, you can write a snap
 If you use [Carthage](https://github.com/Carthage/Carthage), you can add the following dependency to your `Cartfile`:
 
 ``` ruby
-github "pointfreeco/swift-snapshot-testing" ~> 1.1
+github "pointfreeco/swift-snapshot-testing" ~> 1.2
 ```
 
 > ⚠️ Warning: Carthage instructs you to drag frameworks into your Xcode project. Xcode may automatically attempt to link these frameworks to your app target. `SnapshotTesting.framework` is only compatible with test targets, so when you first add it to your project:
@@ -149,7 +149,7 @@ If your project uses [CocoaPods](https://cocoapods.org), add the pod to any appl
 
 ```ruby
 target 'MyAppTests' do
-  pod 'SnapshotTesting', '~> 1.1'
+  pod 'SnapshotTesting', '~> 1.2'
 end
 ```
 
@@ -159,7 +159,7 @@ If you want to use SnapshotTesting in a project that uses [SwiftPM](https://swif
 
 ```swift
 dependencies: [
-  .package(url: "https://github.com/pointfreeco/swift-snapshot-testing.git", from: "1.1.0"),
+  .package(url: "https://github.com/pointfreeco/swift-snapshot-testing.git", from: "1.2.0"),
 ]
 ```