Bug#928617: package-contains-python-header-in-incorrect-directory should be adjusted for python 3.8

[Matthias Klose]

Package: lintian
Version: 2.13.0
Severity: important

Python 3.8 alpha4 dropped the `m' modifier, so /usr/include/python3.8 is not the
correct include dir.  Please reflect that change in lintian.