Log Message:
py-sip6: updated to 6.7.8

v6.7.8 4th April 2023
- The latest version of ABI v13 is v13.5.0.
- The latest version of ABI v12 is v12.12.0.
- The 'wheel-includes' value of the 'tool.sip.project' section of
  pyproject.toml now supports the use of absolute file patterns.
- Replaced the use of the 'toml' package with the standard library 'tomllib'
  package for Python v3.11 and later, and the 'tomli' package for earlier
  versions of Python.
- Bug fixes.