fix: fix public api for non-mobile targets

Author: Uglješa Erceg

Assets/Adjust/Native/iOS/AdjustSdk.framework/Versions.meta

@@ -569,7 +569,6 @@ public static void GetAdid(Action<string> callback)
             AdjustAndroid.GetAdid(callback);
 #else
             Debug.Log(errorMsgPlatform);
-            return string.Empty;
 #endif
         }
 
@@ -586,7 +585,6 @@ public static void GetAttribution(Action<AdjustAttribution> callback)
             AdjustAndroid.GetAttribution(callback);
 #else
             Debug.Log(errorMsgPlatform);
-            return null;
 #endif
         }
 
@@ -604,7 +602,6 @@ public static void GetIdfa(Action<string> callback)
             return;
 #else
             Debug.Log(errorMsgPlatform);
-            return string.Empty;
 #endif
         }
 
@@ -622,7 +619,6 @@ public static void GetIdfv(Action<string> callback)
             return;
 #else
             Debug.Log(errorMsgPlatform);
-            return string.Empty;
 #endif
         }
 
@@ -639,7 +635,6 @@ public static void GetSdkVersion(Action<string> callback)
             AdjustAndroid.GetSdkVersion(callback);
 #else
             Debug.Log(errorMsgPlatform);
-            return string.Empty;
 #endif
         }
 
@@ -657,7 +652,6 @@ public static void GetLastDeeplink(Action<string> callback)
             return;
 #else
             Debug.Log(errorMsgPlatform);
-            return string.Empty;
 #endif
         }