fix: error serialization in resumable-upload.ts

[eagleeye]

Existing error handling has wrong error serialization with .toString(), that leads to [object Object] error messages. Example:
Error: Retry limit exceeded - [object Object]
at Upload.attemptDelayedRetry (/usr/src/app/node_modules/@google-cloud/storage/build/cjs/src/resumable-upload.js:818:26)

Better solution would be JSON.stringify the error

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the issue was discussed with Google Support via DoIT support team as a intermediate

[conventional-commit-lint-gcf]

🤖 I detect that the PR title and the commit message differ and there's only one commit. To use the PR title for the commit history, you can use Github's automerge feature with squashing, or use automerge label. Good luck human!

-- conventional-commit-lint bot
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[ddelgrosso1]

Thank you for the contribution @eagleeye