Fix: ISO string dates shouldn't be considered dates

Author: djhi

src/introspection/getTypeFromValues.js

@@ -20,7 +20,7 @@ const isString = (value) => typeof value === 'string';
 const valuesAreString = (values) => values.every(isString);
 const isArray = (value) => Array.isArray(value);
 const valuesAreArray = (values) => values.every(isArray);
-const isDate = (value) => value instanceof Date || isISODateString(value);
+const isDate = (value) => value instanceof Date;
 const valuesAreDate = (values) => values.every(isDate);
 const isObject = (value) =>
     Object.prototype.toString.call(value) === '[object Object]';

src/introspection/getTypeFromValues.spec.js

@@ -60,13 +60,13 @@ test('returns DateType for Dates', () =>
     expect(
         getTypeFromValues('foo', [new Date('2017-03-15'), new Date()])
     ).toEqual(DateType));
-test('returns DateType for Dates as ISO Strings', () =>
+test('returns GraphQLString for Dates as ISO Strings', () =>
     expect(
         getTypeFromValues('foo', [
             '2022-01-01T00:00:00.000Z',
             '2022-12-01T12:34:56.000Z',
         ])
-    ).toEqual(DateType));
+    ).toEqual(GraphQLString));
 
 test('returns GraphQLJSON for objects', () =>
     expect(