fix(form-data): convert boolean values to strings in FormData serialization (#6917)

lib/helpers/toFormData.js

@@ -120,6 +120,10 @@ function toFormData(obj, formData, options) {
       return value.toISOString();
     }
 
+    if (utils.isBoolean(value)) {
+      return value.toString();
+    }
+
     if (!useBlob && utils.isBlob(value)) {
       throw new AxiosError('Blob is not supported. Use a Buffer instead.');
     }