[release] 1.53.1 - Make defaultValue optional on getValue (#379)

### Improvements
  - Reduced threads needed for initialize
  - Updated error message for OnDeviceEvalAdapter
  - Added a getValue method that doesn't need a defaultValue
  ### Fixes
  - Fixed a potential crash with updateUser





>Included In This Release
>- 9dcfb16 Andre Terron
>   - Prevent crashes on updateUser (#378)
>- 49e65ce devin-ai-integration[bot]
>   - Create a combined store method for initialization values (#374)
>- cbdb6b5 devin-ai-integration[bot]
>   - Update OnDeviceEvalAdapter error message (#377)
>- 74d57b3 Andre Terron
>   - Implement getValue without a defaultValue (#376)

Author: andre-statsig

Sources/Statsig/DeviceEnvironment.swift

@@ -7,7 +7,7 @@ struct DeviceEnvironment {
 
     static internal let deviceOS = PlatformCompatibility.deviceInfo.os
     static internal let sdkType: String = "ios-client"
-    static internal let sdkVersion: String = "1.53.0"
+    static internal let sdkVersion: String = "1.53.1"
 
     let lock = NSLock()
     var sessionID: String? { UUID().uuidString }

Statsig.podspec

@@ -1,7 +1,7 @@
 Pod::Spec.new do |spec|
 
   spec.name         = "Statsig"
-  spec.version      = "1.53.0"
+  spec.version      = "1.53.1"
   spec.summary      = "Statsig enables developers to ship code faster and more safely."
   spec.description  = <<-DESC
                    Statsig enables developers to ship code faster and more safely by providing: