add types to SortOptions [#870]

out of scope for the main thrust of the branch, but quiets the
typechecker.

static-site/src/components/ListResources/index.tsx

@@ -1,4 +1,4 @@
-import React, { Dispatch, SetStateAction, useState, useRef, useEffect } from 'react';
+import React, { Dispatch, FormEvent, SetStateAction, useState, useRef, useEffect } from 'react';
 import styled from 'styled-components';
 import Select, { MultiValue } from 'react-select';
 import ScrollableAnchor from '../../../vendored/react-scrollable-anchor/index';
@@ -160,8 +160,8 @@ export default ListResourcesResponsive
 
 
 function SortOptions({sortMethod, changeSortMethod}) {
-  function onChangeValue(event) {
-    changeSortMethod(event.target.value);
+  function onChangeValue(event:FormEvent<HTMLInputElement>): void {
+    changeSortMethod(event.currentTarget.value);
   }
   return (
     <SortContainer>