Release 3.8.0

Features:
* pmb.chroot: set up PTY support and std I/O nodes
* pmb.qemu.run: Add armv7 support

Fixes:
* kconfigcheck: fix x64_64 typo
* pmb.helpers.pmaports: skip provider search when subpkg definition is empty

Other:
* README.md: Document required git version
* pmb.config.pmaports: automatically switch pmaports branch from master to main