Fix cran warnings for 1.7.

[trivialfis]

#11358

[trivialfis]

winbuilder results:

• https://win-builder.r-project.org/1miKt06iGdgR/
• https://win-builder.r-project.org/rjD7XI0o6yR7/
• https://win-builder.r-project.org/KVCOHm4WXB4F/

[trivialfis]

Flavor: r-devel-linux-x86_64-debian-gcc
Check: for unstated dependencies in 'demo', Result: NOTE
  '::' or ':::' import not declared from: 'caret'
  'library' or 'require' calls not declared from:
    'caret' 'cplm' 'e1071'
  'data(package=)' call not declared from: 'cplm'

[trivialfis]

rhubv2 requires running checks with github actions.

[trivialfis]

Re-submitted.