fix($cli): bump CAC version

[spiltcoffee]

Summary

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• Bugfix
• Feature
• Code style update
• Refactor
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Other information:

Bumping cac to at least v6.3.6 to include the fix for cacjs/cac#34

Since the introduction of cac to vuepress, the command line option --cache [cache] has not worked correctly:

• --cache: cliOptions.cache === true
• --no-cache: cliOptions.cache === false
• --cache /path/to/some/dir: cliOptions.cache === true, targetDir === "/path/to/some/dir"

Since --no-cache is defined, --cache/--no-cache can only be a boolean, and so any argument that you attempt to pass to --cache is interpreted as an individual argument, and in this case becomes the targetDir.

Using at least cac v6.3.6 will correct this behaviour to instead accept the argument passed to --cache into cliOptions.cache as expected:

• --cache: cliOptions.cache === true
• --no-cache: cliOptions.cache === false
• --cache /path/to/some/dir: cliOptions.cache === "/path/to/some/dir"

[ulivz]

Thanks