Fix compatibility with CLI11 2.4.0 and newer
Since CLI11 2.4.0, the '.pvx' file
option is not recognized as a valid
option and results in the following runtime error:
terminate called after throwing an instance of 'CLI::BadNameString'
what(): Invalid positional Name: '.pvx' file
Aborted (core dumped)
Hence, when ParaView is compiled with a new CLI11 version, starting
pvserver
or pvrenderserver
always fails before the user even sees
the result of CLI parsing.
Since the option is deprecated, I don't see much value in actually fixing it and only guarded it with CLI11 version macros, so the option will not be available when a new CLI11 version is used.