tools,win: fix find_python error

On a machine without `python.exe` in the PATH the script was failing
with:

```console
> .\vcbuild.bat
Looking for Python 2.x
2> was unexpected at this time.
```

Escaping the `>` seems to resolve it.

PR-URL: https://github.com/nodejs/node/pull/22797


Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>