BUG: HTTP basic authentication fails with "module 'requests' has no attribute 'HTTPBasicAuth'"

[robertof-surveypal]

Describe the bug
When making a call to an instance of export server protected with HTTP basic authentication the code fails as in

highcharts-core/highcharts_core/headless_export.py

Line 922 in e058b4b

basic_auth = requests.HTTPBasicAuth(auth_user, auth_password)

it tries to access HTTPBasicAuth from requests. The class is exported by requests.auth, as documented at: https://requests.readthedocs.io/en/latest/user/authentication/#basic-authentication

To Reproduce
Steps to reproduce the behavior:

1. When I attempt to export a chart using the following code:

chart.download_chart(
    format="svg",
    timeout=30,
    auth_user="a username",
    auth_password="a password",
)

2. I receive this error: AttributeError: module 'requests' has no attribute 'HTTPBasicAuth'

Expected behavior
The chart is downloaded and available to the calling code.

Your Environment:

• OS: MacOS
• Python Version: 3.12
• Highcharts JavaScript Version: not relevant, the javascript code is not invoked at all

Additional context:
Tested with highcharts-core 1.10.3 and requests 2.32.4

[koushikromel]

Hi — I'd like to work on this issue as a first open-source contribution.

Plan:

• Reproduce the problem locally.
• Fix the import so HTTPBasicAuth is taken from requests.auth.
• Add a small unit test if appropriate and run the test suite.
• Open a PR that references this issue.

I'm new to this project and to open-source contributions, so any guidance, preferred branch/commit message style, or reviewer suggestions would be appreciated. If a maintainer can assign this issue to me, that would help — otherwise I will open a PR once I have the fix ready. Thanks!