build: restore some things lost in the upgrade

Author: wolfy1339

packages/openapi-webhooks-types-ghec/types.d.ts

@@ -2,7 +2,7 @@ import { readdir, mkdir, rm, writeFile, copyFile } from "node:fs/promises";
 import { basename } from "node:path";
 
 import * as prettier from "prettier";
-import openapiTS, { astToString } from "openapi-typescript";
+import openapiTS, { astToString, COMMENT_HEADER } from "openapi-typescript";
 import { pathToFileURL } from "node:url";
 
 /* (!process.env.OCTOKIT_OPENAPI_VERSION) {
@@ -88,9 +88,10 @@ type Repository = components["schemas"]["full-repository"]
     await writeFile(
       `packages/${packageName}/types.d.ts`,
       await prettier.format(
-        astToString(
+        COMMENT_HEADER + astToString(
           await openapiTS(
             pathToFileURL(`packages/openapi-webhooks/generated/${name}.json`),
+            { defaultNonNullable: false,  }
           ),
         ),
         {