fix CphTest with number arguments

[kakig]

This pull request fixes an issue when using CphTest with arguments.

Running CphTest 1 gives the following error:

E5108: Error executing lua Vim:E484: Can't open file inputinput1
stack traceback:
        [C]: in function 'readfile'
        ...ack/packer/start/cphelper.nvim/lua/cphelper/run_test.lua:15: in function 'run_test'
        ...acker/start/cphelper.nvim/lua/cphelper/process_tests.lua:30: in function 'iterate_cases'
        ...acker/start/cphelper.nvim/lua/cphelper/process_tests.lua:102: in function 'process_retests'
        ...acker/start/cphelper.nvim/lua/cphelper/process_tests.lua:94: in function 'process'
        [string ":lua"]:1: in main chunk
Press ENTER or type command to continue

It seems like the case variable was already the complete filename, so by prepending "input", we ended up with inputinput1 as filename, which doesn't exist. I just removed the prepending part of the code.

[p00f]

This doesn't make sense though - the command CphTest passes its arguments as-it-is to process_tests.process, which passes them as-it-is to iterate_cases

[p00f]

If i print the case_numbers table in iterate_cases I get { "1" }

[p00f]

If I print case before this line https://github.com/p00f/cphelper.nvim/blob/4bc91f27a29dad0eaeda6c3470924f6e1174f4aa/lua/cphelper/process_tests.lua#L30 I get only 1

[p00f]

Ah understood

[p00f]

Thanks!