Change gsub! to gsub so that we don't end up with nil errors when a match isn't found

Author: gwillcox-r7

modules/exploits/windows/http/hpe_sim_76_amf_deserialization.rb

@@ -99,7 +99,8 @@ def check
   def exploit
     case target['Type']
     when :windows_command
-      execute_command(payload.encoded.gsub!(/^powershell(?:\.exe)* /, 'C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe ')) # If PowerShell is being used to run the command, specify the full path so that it will run correctly.
+      require 'pry'; binding.pry
+      execute_command(payload.encoded.gsub(/^powershell(?:\.exe)* /, 'C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe ')) # If PowerShell is being used to run the command, specify the full path so that it will run correctly.
     when :windows_powershell
       execute_command(cmd_psh_payload(payload.encoded, payload.arch.first, remove_comspec: true).prepend('C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\')) # Need full path to PowerShell binary for it to run for some reason.
     end