update to 0.8.0

Created by: jmitrevs

Description

This changes the version of hls4ml in documentation to 0.8.0.

Type of change

• Other (Specify)

Tests

Look at web pages and build the documentation

Checklist

• I have read the guidelines for contributing.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• I have installed and run pre-commit on the files I edited or added.
• I have added tests that prove my fix is effective or that my feature works.