Remove -beta suffix from CFBundleShortVersionString (segmentio#795)

**What does this PR do?**

This allows for the framework to be used in Swift 4 projects who consume this framework from Carthage, to be submitted to the App Store.

Closes segmentio#794

**Where should the reviewer start?**

By reading segmentio#794

**How should this be manually tested?**

Create a project with Swift 4, consume this framework with Carthage, and then submit it to the App Store 😅

**Any background context you want to provide?**

segmentio#794

**What are the relevant tickets?**

segmentio#794

Analytics/Info.plist

@@ -15,7 +15,7 @@
 	<key>CFBundlePackageType</key>
 	<string>FMWK</string>
 	<key>CFBundleShortVersionString</key>
-	<string>3.7.0-beta</string>
+	<string>3.7.0</string>
 	<key>CFBundleVersion</key>
 	<string>$(CURRENT_PROJECT_VERSION)</string>
 	<key>NSPrincipalClass</key>

RELEASING.md

@@ -16,6 +16,6 @@ Releasing
  9. Create a new Github release at https://github.com/segmentio/analytics-ios/releases
      * Add latest version information from `CHANGELOG.md`
      * Upload `Archive.zip` from step 7 and `Analytics.zip` from step 8 into binaries section to make available for users to download.
- 10. Update the version in `SEGAnalytics.m`, `Analytics.podspec` and `Analytics/Info.plist` to the next SNAPSHOT version.
+ 10. Update the version in `SEGAnalytics.m`, `Analytics.podspec` to the next SNAPSHOT version.
  11. `git commit -am "Prepare next development version."`
  12. `git push`.