Update identity CODEOWNERS (Azure#2421)

Co-authored-by: Heath Stewart <[email protected]>

Author: chlowell

.github/CODEOWNERS

@@ -45,7 +45,7 @@
 # AzureSDKOwners: @heaths
 # ServiceLabel: %Azure.Identity
 # PRLabel: %Azure.Identity
-/sdk/identity/           @heaths @RickWinter @LarryOsterman
+/sdk/identity/           @heaths @RickWinter @LarryOsterman @chlowell
 
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 # Client SDKs