Server: remove unused imports in _query

Author: dshemetov

src/server/_query.py

@@ -10,18 +10,16 @@
     Tuple,
     Union,
     cast,
-    Mapping,
 )
 from flask import Response
 
 from sqlalchemy import text
 from sqlalchemy.engine import Row
 
 from ._common import db, app
-from ._db import metadata
 from ._printer import create_printer, APrinter
 from ._exceptions import DatabaseErrorException
-from ._validate import DateRange, extract_strings
+from ._validate import extract_strings
 from ._params import GeoPair, SourceSignalPair, TimePair
 from .utils import time_values_to_ranges, days_to_ranges, weeks_to_ranges