Fix missing imports (#1067)

Author: rzats

src/server/endpoints/ecdc_ili.py

@@ -1,6 +1,6 @@
 from flask import Blueprint
 
-from .._params import extract_integers, extract_strings
+from .._params import extract_integer, extract_integers, extract_strings
 from .._query import execute_query, QueryBuilder
 from .._validate import require_all
 

src/server/endpoints/flusurv.py

@@ -1,6 +1,6 @@
 from flask import Blueprint
 
-from .._params import extract_integers, extract_strings
+from .._params import extract_integer, extract_integers, extract_strings
 from .._query import execute_query, QueryBuilder
 from .._validate import require_all
 

src/server/endpoints/fluview_clinicial.py

@@ -1,6 +1,6 @@
 from flask import Blueprint
 
-from .._params import extract_integers, extract_strings
+from .._params import extract_integer, extract_integers, extract_strings
 from .._query import execute_query, QueryBuilder
 from .._validate import require_all