fix(types): add Buffer to WhereValue type (#11499)

Author: fubar

types/lib/model.d.ts

@@ -341,6 +341,7 @@ export type WhereValue =
   | string // literal value
   | number // literal value
   | boolean // literal value
+  | Buffer // literal value
   | null
   | WhereOperators
   | WhereAttributeHash // for JSON columns

types/test/where.ts

@@ -9,6 +9,18 @@ let where: WhereOptions;
 
 // From https://sequelize.org/master/en/v4/docs/querying/
 
+/**
+ * Literal values
+ * @see WhereValue
+ */
+where = {
+  string: 'foo',
+  number: 1,
+  boolean: true,
+  buffer: Buffer.alloc(0),
+  null: null,
+};
+
 // Operators
 
 const and: AndOperator = {