chore: Update Python version in main.yaml action (#13473)

The Github action in
[main.yaml](https://github.com/googleapis/google-cloud-python/blob/main/.github/workflows/main.yml)
has been failing with the following error:

```
The version '3.10.0' with architecture 'x64' was not found for Ubuntu 24.04.
The list of all available versions can be found here: https://raw.githubusercontent.com/actions/python-versions/main/versions-manifest.json
```

It's not necessary to specify the specific patch version of Python 3.10
that is required, for example `3.10.0`, instead of `3.10`. The latest
version of `3.10` should work.


https://github.com/googleapis/google-cloud-python/blob/f699e5fd6a6618526da1b2cb3e90bf95314f89a5/.github/workflows/main.yml#L45-L48

Co-authored-by: Victor Chudnovsky <[email protected]>

Author: parthea

.github/workflows/main.yml

@@ -45,7 +45,7 @@ jobs:
       - name: Set up Python 3.10
         uses: actions/setup-python@v5
         with:
-          python-version: 3.10.0
+          python-version: "3.10"
       - name: Install script dependencies
         run: pip3 install -r requirements.txt
         working-directory: ./scripts