filter empty packages from database

In some cases (e.g. during addition of the package to build queue) we don't have
full information about package inself; in these cases we produce lines
with empty architecture, which duplicates normal ones.

This commit changes architecture column type to required and also
filters packages which don't have architecture set yet.

Closes #83

tests/ahriman/core/database/migrations/test_m006_packages_architecture_required.py

@@ -0,0 +1,8 @@
+from ahriman.core.database.migrations.m006_packages_architecture_required import steps
+
+
+def test_migration_logs() -> None:
+    """
+    migration must not be empty
+    """
+    assert steps

tests/ahriman/core/database/operations/test_package_operations.py

@@ -48,6 +48,16 @@ def test_package_update_insert_packages(database: SQLite, connection: Connection
     connection.executemany(pytest.helpers.anyvar(str, strict=True), pytest.helpers.anyvar(int))
 
 
+def test_package_update_insert_packages_no_arch(database: SQLite, connection: Connection,
+                                                package_ahriman: Package) -> None:
+    """
+    must skip package insertion if no package architecture set
+    """
+    package_ahriman.packages[package_ahriman.base].architecture = None
+    database._package_update_insert_packages(connection, package_ahriman)
+    connection.executemany(pytest.helpers.anyvar(str, strict=True), [])
+
+
 def test_package_update_insert_status(database: SQLite, connection: Connection, package_ahriman: Package) -> None:
     """
     must insert single package status