[TC-221]: init template-backend-service (#1)

https://eva.avroid.tech/desk/cards?obj=Task:TC-221

Начальная версия сервиса-шаблона

Co-authored-by: Nadezhda <nadezhda.lavrentieva@avroid.team>
Reviewed-on: https://git.avroid.tech/Templates/template-backend-service/pulls/1
Reviewed-by: Victor Stratov <victor.stratov@avroid.tech>

migrations/script.py.mako

@@ -0,0 +1,26 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision: str = ${repr(up_revision)}
+down_revision: Union[str, None] = ${repr(down_revision)}
+branch_labels: Union[str, Sequence[str], None] = ${repr(branch_labels)}
+depends_on: Union[str, Sequence[str], None] = ${repr(depends_on)}
+
+
+def upgrade() -> None:
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    ${downgrades if downgrades else "pass"}