Gsutil addlhelp crc32c should be updated to account for PEP 668

`gslib/addlhelp/crc32c.py` describes a nasty issue where `gsutil` does not come with a pre-compiled version of `crcmod`. In order to ensure the version is compiled it suggests running the following for ubuntu distros:
```sh
sudo apt-get install gcc python3-dev python3-setuptools
sudo pip3 uninstall crcmod
sudo pip3 install --no-cache-dir -U crcmod
```

On Ubuntu 24 which has python3.12 as the system python, this results in an error:

What are the updated instructions for ensuring a compiled version of `crcmod` is installed on an ubuntu 24 machine?

I do see that the ubuntu 24 machines i have provisioned have the gsutil version that comes with crcmod precompiled:
```
$ gsutil version -l | grep crcmod
compiled crcmod: True
```
Is the compiling issue a stale issue and we no longer have to deal with it on Ubuntu 24 or should the addlhelp be updated? Thanks!

Start with gslib/addlhelp/crc32c.py and review the Ubuntu instructions against PEP 668 on Ubuntu 24 with Python 3.12. Run the documented commands and gsutil version -l to verify whether crcmod is already compiled; done means the help text clearly states the current supported steps or explains that compilation is no longer needed.

Written by the indexing model from the issue text.