fix Error [ERR_UNSUPPORTED_ESM_URL_SCHEME] when using a artillery runner file with a .mjs extension

[thrandale]

This fixes issue #2661

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[hassy]

thanks @thrandale! Is the issue due to a missing relative path? ie. in your example ./artilleryRunner.mjs should work as expected (if the MJS file is in the same directory as the YAML script). There's a test for loading ESM here, would you mind updating that please? https://github.com/artilleryio/artillery/blob/242a7964934851bf77e53eebf44e6312de723663/packages/artillery/test/cli/async-hooks-esm.test.js

[thrandale]

@hassy Even using a relative path, it still fails with the same error. When it does the path.resolve(), that resolve either an absolute or relative path to an absolute path. It is odd that it is not failing in the CI. I believe this is only an issue on Windows. Does the CI run the windows tests?