Update cq_client in depot_tools form CQ repo

third_party/cq_client/cq.proto

 syntax = "proto2";
 
 // This message describes a Commit Queue configuration. The config file cq.cfg
 // should be stored in the config directory located on the branch that this CQ
 // should commit to.
 message Config {
   // Required. Version of the config format.
   optional int32 version = 1;
 
   // Required. Name of the CQ. May only contain characters [a-zA-Z0-9_]. It is
@@ skipping 37 matching lines @@
   // source repository is not supported by luci-config (e.g. GitHub).
   optional string git_repo_url = 10;
 
   // Target ref to commit to. This can be used to specify a different ref than
   // the one where the luci config is located. This is useful, e.g. for projects
   // that use gnumbd where CQ should commit into a pending ref.
   optional string target_ref = 11;
 
   // Deprecated. URL of the SVN repository. We are deprecating SVN support.
   optional string svn_repo_url = 12;
+
+  // If present, the CQ will refrain from processing any commits whose start
+  // time is >= this time.
+  //
+  // This is an UTC RFC3339 (stiptime(tm)) string representing the time.
+  optional string draining_start_time = 13;
 }
 
 message Rietveld {
   // Required. URL of the codereview site.
   optional string url = 1;
 
   // List of regular expressions used to check if CL's base URL should be
   // processed by this CQ. This may be useful if a single branch has multiple
   // sub-directories that are handled by different CQs. When no regular
   // expressions are specified, the regular expression '.*', which matches any
@@ skipping 124 matching lines @@
       optional int32 timeout_retry_weight = 5;
     }
 
     // Provides project specific trybot retry configuration. This overrides the
     // defaults used in the CQ.
     optional TryJobRetryConfig try_job_retry_config = 2;
   }
 
   message SignCLAVerifier {}
 }