test: make sure the file checked doesn't change with .gitignore

The integration repositories are clean and should not contain any extra files. If the `--gitignore` option ignores any of those files, then something is wrong. This check would have caught #1846.

integration-tests/src/check.ts

@@ -12,7 +12,7 @@ import { PrefixLogger } from './PrefixLogger';
 import { Logger } from './types';
 
 const config = readConfig();
-const cspellArgs = '-u --no-progress --relative --show-context';
+const cspellArgs = '-u --no-progress --relative --show-context --gitignore --gitignore-root=. ';
 const jsCspell = JSON.stringify(Path.resolve(__dirname, '..', '..', 'bin.js'));
 
 const cspellCommand = `node ${jsCspell} ${cspellArgs}`;