Deck convert from 2.x to 3.x does not handle the escape characters in the regex paths

Input
``` yaml
routes:
- https_redirect_status_code: 426
methods:
- POST
name: excelReader-route
path_handling: v0
paths:
- /excelReader/([^\/]+)
```

`deck file convert --from kong-gateway-2.x --to kong-gateway-3.x --input-file {input_file} --output-file {output_file}`

Expected output:
``` yaml
routes:
- https_redirect_status_code: 426
methods:
- POST
name: excelReader-route
path_handling: v0
paths:
- /excelReader/([^/]+)
```

After converted file from 2.x to 3.x output, while syncing got an below error

```
while processing event: Create route excelReader-route failed: HTTP status 400 (message: "validation error")
```

Reproduce the issue with the `deck file convert --from kong-gateway-2.x --to kong-gateway-3.x` command and the YAML route containing `/excelReader/([^\\/]+)`. Trace the conversion path for route regex paths and verify that the converted output uses `/excelReader/([^/]+)` and can sync successfully without the validation error.

Written by the indexing model from the issue text.