cxxopts: conan v2 support

[SpaceIm]

Specify library name and version: lib/1.0

This is also a good place to share with all of us why you are submitting this PR (specially if it is a new addition to ConanCenter): is it a dependency of other libraries you want to package? Are you the author of the library? Thanks!

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• I've read the guidelines for contributing.
• I've followed the PEP8 style guides for Python code in the recipes.
• I've used the latest Conan client version.
• I've tried at least one configuration locally with the conan-center hook activated.

[conan-center-bot]

Conan v1 pipeline

All green in build 1 (f35119b1a45cbec19205f6b6afb3fb6d0aca399f):

• cxxopts/2.2.1@:
  All packages built successfully! (All logs)

• cxxopts/2.2.0@:
  All packages built successfully! (All logs)

• cxxopts/3.0.0@:
  All packages built successfully! (All logs)

• cxxopts/1.4.4@:
  All packages built successfully! (All logs)