Bump up version for Az.CosmosDB

Author: wyunchi-ms

src/CosmosDB/CosmosDB/Az.CosmosDB.psd1

@@ -53,7 +53,7 @@ DotNetFrameworkVersion = '4.7.2'
 # ProcessorArchitecture = ''
 
 # Modules that must be imported into the global environment prior to importing this module
-RequiredModules = @(@{ModuleName = 'Az.Accounts'; ModuleVersion = '2.16.0'; })
+RequiredModules = @(@{ModuleName = 'Az.Accounts'; ModuleVersion = '2.15.1'; })
 
 # Assemblies that must be loaded prior to importing this module
 RequiredAssemblies = 'Microsoft.Azure.PowerShell.CosmosDB.Management.Sdk.dll',