I would assume that the tool will need some coding to get it compatible again..?
yes, of course, we need to make a migration to new versions of SALESFORCE API.
But you can try this soluction
When a new version of Salesforce is released to Sandbox environments, the default API version of Salesforce is incremented in the Workbench API tool. This is not yet a valid option for Production environments, so if you attempt to log into Workbench with a Production or Developer org, this error can appear.
To correct this error, make the following changes in Workbench:
Hover over the Workbench label
Select 'Settings' in the dropdown
Change 'Default API Version' to one version lower. For example, if the selected API version is 40.0 and you are receiving this error, change the API version to 39.0.
Click 'Apply Settings' at the bottom of the page
Select the Workbench icon in the taskbar from your org again, and it should now behave as designed
This option is saved in the browser cache. If you clear your cache or use an incognito browser, you will need to update this setting again.
Let me know!