Add ExpireMachine spec to rpc

proto/headscale/v1/headscale.proto

@@ -92,6 +92,12 @@ service HeadscaleService {
         };
     }
 
+    rpc ExpireMachine(ExpireMachineRequest) returns (ExpireMachineResponse) {
+        option (google.api.http) = {
+            post: "/api/v1/machine/{machine_id}/expire"
+        };
+    }
+
     rpc ListMachines(ListMachinesRequest) returns (ListMachinesResponse) {
         option (google.api.http) = {
             get: "/api/v1/machine"

proto/headscale/v1/machine.proto

@@ -64,6 +64,14 @@ message DeleteMachineRequest {
 message DeleteMachineResponse {
 }
 
+message ExpireMachineRequest {
+    uint64 machine_id = 1;
+}
+
+message ExpireMachineResponse {
+    Machine machine = 1;
+}
+
 message ListMachinesRequest {
     string namespace = 1;
 }