fix(bson-transpilers-python-regex): No need to escape `\` in regex

[mingjun97]

Description

Remove the escape sentence as the returned value is using r string and no need to append double \ to escape characters.

Checklist

• [ ] New tests and/or benchmarks are included
• [ ] Documentation is changed or added
• [X] I have signed the MongoDB Contributor License Agreement (https://www.mongodb.com/legal/contributor-agreement)

Motivation and Context

• [x] Bugfix
• [ ] New feature
• [ ] Dependency update
• [ ] Misc

While using export to python the following query

{message: {$regex: /\d+/}}

will be translated into

{
    'message': {
        '$regex': re.compile(r"\\d+")
    }
}

---

The expected outcome should be:

{
    'message': {
        '$regex': re.compile(r"\d+")
    }
}

or

{
    'message': {
        '$regex': re.compile("\\d+")
    }
}

Since r string(r"") is used in the return value, an extra escape for the \ is redundant and breaks the semantic of the original regex.

Open Questions

Dependents

Types of changes

• [ ] Backport Needed
• [x] Patch (non-breaking change which fixes an issue)
• [ ] Minor (non-breaking change which adds functionality)
• [ ] Major (fix or feature that would cause existing functionality to change)