fix: Update launchdarkly_dart_common to version 1.8.1 (#277)

<!-- CURSOR_SUMMARY -->
> [!NOTE]
> **Low Risk**
> Dependency-only patch version bump with no application logic changes
in this PR.
> 
> **Overview**
> Bumps the `launchdarkly_dart_common` dependency in
`packages/common_client` from **1.8.0** to **1.8.1** (patch release).
> 
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Author: kinyoklion

packages/common_client/pubspec.yaml

@@ -9,7 +9,7 @@ environment:
 
 dependencies:
   http: ^1.1.2
-  launchdarkly_dart_common: 1.8.0
+  launchdarkly_dart_common: 1.8.1
   launchdarkly_event_source_client: 2.1.0
   crypto: ^3.0.3
   uuid: ">= 3.0.7 <5.0.0"