Change the :type of pytest-at-point debug template

[gamboz]

The :type of the debug template "Python :: Run pytest (at point)" should match the "LANGUAGE-ID" argument of the function (dap-register-debug-provider), otherwise the "PROVIDE-CONFIGURATION-FN" is not called (and all tests in the current buffer are run, instead of just the test function at point).

I also humbly suggest to edit the doc string of (dap-register-debug-provider) so that it explicitly references the name of the property :type of the plist "CONFIGURATION-SETTINGS" in (dap-register-debug-template). I'm not providing a MR for this because it's entirely possible that the problem is actually me not understanding what's going on here :slightly_smiling_face: