Drop removed_time column on topics

This column wasn't being used, and the TopicLog can handle it.

tildes/alembic/versions/a1708d376252_drop_topics_removed_time_column.py

@@ -0,0 +1,32 @@
+"""Drop topics.removed_time column
+
+Revision ID: a1708d376252
+Revises: bcf1406bb6c5
+Create Date: 2018-08-23 00:29:41.024890
+
+"""
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+
+# revision identifiers, used by Alembic.
+revision = "a1708d376252"
+down_revision = "bcf1406bb6c5"
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.drop_column("topics", "removed_time")
+
+
+def downgrade():
+    op.add_column(
+        "topics",
+        sa.Column(
+            "removed_time",
+            postgresql.TIMESTAMP(timezone=True),
+            autoincrement=False,
+            nullable=True,
+        ),
+    )

tildes/tildes/models/topic/topic.py

@@ -92,7 +92,6 @@ class Topic(DatabaseModel):
     is_removed: bool = Column(
         Boolean, nullable=False, server_default="false", index=True
     )
-    removed_time: Optional[datetime] = Column(TIMESTAMP(timezone=True))
     title: str = Column(
         Text,
         CheckConstraint(f"LENGTH(title) <= {TITLE_MAX_LENGTH}", name="title_length"),