alembic: increase uri column size

When mobile SIP clients register with Asterisk that use some sort of
push notifications, the URI can get quite lengthy due to the
additional push-service annotations (things like tokens, pn-type, etc.)
contained in it.

ASTERISK-28022 #close

Change-Id: I4c7ceadc3bb405f3daf722641c8cd5ca4188cc37

contrib/ast-db-manage/config/versions/1d3ed26d9978_increase_uri_column_size.py

+"""Increase uri column size
+
+Revision ID: 1d3ed26d9978
+Revises: 19b00bc19b7b
+Create Date: 2018-08-23 11:46:13.283801
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '1d3ed26d9978'
+down_revision = '19b00bc19b7b'
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    op.alter_column('ps_contacts', 'uri', type_=sa.String(511))
+
+
+def downgrade():
+    op.alter_column('ps_contacts', 'uri', type_=sa.String(255))