Run mypy from tox

This avoids the need to duplicate our dependency list in multiple places
and allows us to take advantage of tox's dependency management
infrastructure, to ensure we always get the latest and greatest version
of a package allowed by upper-constraints. It also removes the slowest
pre-commit hook (by some distance), making pre-commit faster.

Change-Id: Ie241768231f180d5a672bf9f8fdc6a1eb8d7dfdb
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

pyproject.toml

@@ -124,7 +124,6 @@ follow_imports = "skip"
 incremental = true
 check_untyped_defs = true
 warn_unused_ignores = true
-# keep this in-sync with 'mypy.exclude' in '.pre-commit-config.yaml'
 files = [
     "nova/compute/manager.py",
     "nova/compute/pci_placement_translator.py",