feat: add PackageBase.MetaModifiedTS column

Since we cannot depend on InnoDB features across all mysql
installations, we are instead using this new column to track
metadata changes for a particular package base.

This will allow us to fetch less data when producing metadata
archives for end-users, and it does not depend on installation
details aside from the schema/migrations being applied.

New columns:
- `PackageBase`.`MetaModifiedTS`

Signed-off-by: Kevin Morris <kevr@0cost.org>

test/test_migrations.py

@@ -0,0 +1,49 @@
+import pytest
+
+from aurweb import db
+from aurweb.models import PackageBase, User
+from aurweb.time import utcnow
+
+
+@pytest.fixture(autouse=True)
+def setup(db_test: None) -> None:
+    pass
+
+
+@pytest.fixture
+def user() -> User:
+
+    with db.begin():
+        user_ = db.create(User, Username="test", Email="test@example.org")
+
+    yield user_
+
+
+@pytest.fixture
+def pkgbase(user: User) -> PackageBase:
+    now = utcnow()
+
+    with db.begin():
+        pkgbase_ = db.create(
+            PackageBase,
+            Name="pkg",
+            ModifiedTS=now,
+            MetaModifiedTS=now,
+            SubmittedTS=now,
+            Maintainer=user,
+            Packager=user,
+        )
+
+    yield pkgbase_
+
+
+def test_package_base_columns(user: User, pkgbase: PackageBase):
+    assert pkgbase.Name == "pkg"
+
+    assert bool(pkgbase.SubmittedTS)
+    assert bool(pkgbase.ModifiedTS)
+    assert bool(pkgbase.MetaModifiedTS)
+
+    assert pkgbase.Maintainer == user
+    assert pkgbase.Packager == user
+    assert pkgbase.Flagger is None